Monday, December 24, 2012

A Story of the Season

It’s a moving Christmas story (of sorts) that Giles Miller, Curator of Micropalaeontology at the Natural History Museum, London, tells on his blog.  The occasion for the telling of this tale is the 100th anniversary of a wonderful microscope slide presented by Arthur Earland to Edward Heron-Allen for Christmas in 1912.  A real treat in this fascinating post are the photographs of some of Earland’s slides (Christmas or otherwise).  Reportedly, there was once a slide on which Earland mounted 1,500 foraminifera shells!  (I’ve written previously on my blog about Earland’s Christmas slides on which he painstakingly affixed foraminifera shells in elaborate designs, replete with the year, the season, and his initials.)

Miller recounts how the two men, amateur micropaleontologists working out of the British Museum, had a long collaboration which produced many seminal works on foraminifera, a collaboration which lasted until they had a mysterious and irreconcilable falling out in the early 1930s.  Heightening the intrigue of the rupture between the two men is Earland's reference to “that final woman.”  For some reason (perhaps the two men just look the part), I am reminded of Irene Adler, who was to Sherlock Holmes “always the woman.”

Miller’s blog post is very enjoyable reading in this Christmas season.  Happy New Year.

Saturday, December 22, 2012

Volcanic Pipe Dreams ~ Maps With a View

I have a love-hate relationship with geologic maps which are so often both strikingly beautiful and challengingly complex.  I am drawn to them because they are begging to be read, the swatches of color spread across them hint at wonderful geologic stories.  But, at this stage, I can only enjoy the hints, I just don’t have the necessary grasp of the science or the language to do more.

My latest adventure with geologic maps came earlier this month after Washington Post columnist John Kelly wrote about two volcanoes in Virginia that saw action during the Eocene Epoch (Hidden Depths:  The Mystery of Virginia’s Extinct Volcanoes,  December 15, 2012).  Mole Hill, just to the west of Harrisonburg, Virginia, and Trimble Knob, just outside of Monterey, Virginia, are the very eroded remains of extinct volcanoes.  Courtesy of Google Maps, here’s where they are (the blue markers).

And here's what they look like.

Mole Hill

(This image has been released into the public domain by its author, Jstuby and is available on Wikipedia.)

Trimble Knob

(This image is by Raph Levien and reproduced under a Creative Commons Attribution 3.0 License.  It is available on Wikipedia.)

These volcanoes are a geologic surprise and a puzzle.  The surprise is their age.  Before 1969, the accepted wisdom was that these volcanic remains were no different from nearly all of the other igneous rock in the Blue Ridge and Piedmont provinces that go back hundreds of millions of years.  But, beginning in 1969, analyses of the rocks at these sites have produced estimates that place these volcanoes in the Eocene Epoch (about 56 to 34 million years ago), making them collectively “the youngest igneous rocks in the Eastern United States.”  (C. Scott Southworth, et al., Middle Eocene Intrusive Igneous Rocks of the Central Appalachian Valley and Ridge Province – Setting, Chemistry, and Implications for Crustal Structure, U.S. Geological Survey Bulletin 1839, 1993, p. J17)

The puzzle posed by these volcanic remains emerges from, again, their age.  This area during this Eocene time frame had been thought to be quiescent.  But not now, and, so, the debate is on.  What caused this volcanic activity?  Southworth et al. concluded that the action here during the Eocene was geologically very brief (a few million years), limited in scope, and, on occasion, explosive.  They argued that the volcanic activity at this place and at this time might be best explained by a reopening of basement fractures (the basement is the level below which sedimentary rock does not appear) and a global change in plate tectonic movement that occurred around this time.

Kelly’s article features Elizabeth Johnson, a geologist at James Madison University which is located in Harrisonburg, Mole Hill’s backyard.  These and other extinct volcanoes have become teaching tools.  The focus of her research and, by extension, that of her students, is on the material carried or exploded to the surface.  The central question is what does that material reveal about the Earth’s crust and the depth of the mantle here.

After reading Kelly’s piece and some of the available research on these geological phenomena, I went in search of Mole Hill and Trimble Knob.  Well, actually I stayed at my computer and set out to find geologic maps with a view of these two sites.

A friend of mine approaches our book club books by reading the first few pages and then skipping to the end to read the dénouement.  If the conclusion’s of any interest (and not upsetting), she’ll go back and read the entire book.  Though that’s not how I deal with books, there’s a certain logic for a neophyte coming to geologic maps to be forearmed with a sense of what the maps are intended to tell.  At least, I have a fighting chance of interpreting the language of the maps.

What follows makes it all seem so much more straightforward than it really was.  I’ll even skip going off on how much remains to be done to bring order to the world of maps from state geological surveys and the U.S. Geological Survey, partly because there does seem to have been some progress.  A case in point is the National Geologic Map Database being assembled by the USGS.  Sadly, though, Virginia is the only state on the East Coast included in the very useful MapView product in the Database.  And I have already vented on this topic in an earlier blog post.

Here is a segment of a statewide geologic map prepared by the Virginia Division of Mineral Resources in 1993 (digitized in 2003).

The arrows point to the towns of Monterey (to the west) and Harrisonburg (to the east), not to the volcanic remains which really don’t appear in this map given its small scale – 1:500,000.  At this scale, 1 inch on the map equals 500,000 inches or approximately 7.89 miles, which makes it useful for a broad picture, but not for exploring the geology of these two volcanic sites.  [Note:  I corrected my description of this scale in response to the gracious comment from Silver Fox.  See below.]

Maps with a scale of 1:24,000 give enough detail to focus on Mole Hill and Trimble Knob.  At this scale, 1 map inch equals 2,000 feet or approximately 0.38 miles.  Here is Mole Hill in a 1986 map prepared by the Virginia Division of Mineral Resources (T.M. Gathright, II, and P.S. Frischmann, Geology of the Harrisonburg and Bridgewater Quadrangles, Publication 60, 1986).

The “Tv” symbol in Mole Hill’s orange blob indicates that this is considered a “volcanic pipe.”  As I understand it, the pipe is the passageway through which the magma travels upward.  Upon the death of the volcano, the solidified magma in the pipe proves more resistant to erosion and so is often the last vestige of the volcano.  (Reed Wicander, et al., Essentials of Geology, 2006, p. 90.)  I suspect it's important that Mole Hill is bracketed by faults.  The dotted lines that originate from a point just to the southwest of the hill are used to represent fault lines that are either covered over or inferred by the geologist preparing the map.  “U” indicates the “upthrown side” of the fault (rocks here are displaced upwardly), while “D” is the “downthrown side” (downward displacement).  The light pink that surrounds Mole Hill is identified as “Obud” or the upper dolomite unit of the Beekmantown Group.  This is Ordovician limestone.

Had I expected to find something similar in the maps of Trimble Knob, I would have been disappointed.  As it was, I wasn’t burdened with any expectation, because I invested too much energy struggling to find the appropriate map.  That turned out to be Geologic Map of the Monterey Quadrangle, Virginia (Gerald P. Wilkes, Virginia Division of Geology and Mineral Resources, Publication 178, 2011, scale 1:24,000).

 Hmmm, no indication of a volcanic pipe in this map.  Instead, the pinkish tan blob labeled Trimble Knob carries the letter “b” for “breccia.”  Breccia consists of unworn, coarse rock fragments, often cemented together by a clay matrix.  The map’s author describes the breccia material here as “volcanic, dark-gray to black” with “poorly sorted xenoliths of sedimentary and igneous rock . . . .”  Xenoliths include material from the so-called “country rock,” that is, the layer of original rock through which the volcanic magma penetrated.  In many ways, these are messengers from deep underground.  They are what geologist Elizabeth Johnson analyzes in her effort to comprehend the mantle and crust beneath the Shenandoah Valley.  The pale blue that washes around Trimble Knob represents rock from the Devonian Millboro Shale and Needmore Formation.

I actually don’t think it’s significant that the geologic map depicting Mole Hill appears to differ so much from that for Trimble Knob.  Perhaps it’s just a function of a quarter century (1986 to 2011) of evolving standards and practices in making geologic maps, or different views of different geologist authors.  Geologists Jonathan L. Tso and John D. Surber describe these igneous features in this part of the Shenandoah as “the old plumbing system that once fed a volcanic complex that has since been eroded away.  The larger bodies such as Trimble Knob and Ugly Mountain [West Virginia], may represent old volcanic necks or pipes.”  (Eocene Igneous Rocks Near Monterey, Virginia:  A Field Study, Virginia Minerals, August/November 2006, p. 9).  

The images that open this post and the geologic maps that close it, attest to the fact that we are witnessing the final episode in the life of two volcanoes.  Of course, we won't be here when the last chapter ends.  I think it's fitting to finish with an observation from geologist and paleontologist Ellis W. Shuler (1881 - 1954) about the life spans of volcanoes.  Shuler grew up in rural Virginia during the late 19th century, and, as I described in an earlier post, he opens his book Rocks and Rivers by recounting his first encounter with geology and paleontology.  As a boy of 14, just after reading The Last Days of Pompeii, several earthquakes hit the area around his town of Pearisburg, Virginia (165 miles southwest of Harrisonburg).  Shuler was convinced that Angel's Rest, a mountain that overlooked the town, was about to blow.  The geologist sent from the USGS to explore the causes of this seismic activity befriended the boy and sparked a lifelong interest in geology and paleontology.  There's a poetic touch to Shuler's observation about the ultimate demise of a volcano:
In the end extinction comes to all volcanoes.  Pressures which force up the lavas are relieved and the explosive gases escape.  The volcanic rocks decay to rich soils, and these soils in turn are eroded away.  Volcanic necks, the hard inner core or pipe, survive longest, but these too finally disappear; and the plains of erosion sweep across the site.  The volcanic episode is closed.  (Rocks and Rivers, 1945, p. 170)

Saturday, December 8, 2012

Scientific Poetry

The scientific literature I’ve read recently on my microorganisms of choice – ostracodes and foraminifera – surprised me.  In two of these texts, I found, of all things, poetry.  Prompted by these stray bits of verse, I’ve been considering the nexus of science and poetry.  The idiosyncrasies and limits of my initial exploration are, for better or worse, reflected in this post.

(Ostracodes are tiny crustaceans and foraminifera are single-celled protists.  The shelly fossilized remains of each have figured in several previous posts.)

Crystallographer Alan L. Mackay has asserted that scientific poetry comes in two categories, the first fairly abounding with poems, the second sparsely populated.  (Rhyme and Reason, The Sciences, July/August, 1981.)

The more common is the infusion of scientific terms and concepts into poetry to explore some universal truth.

Among the many examples one could read, let me offer one I particularly like.  Roald Hoffmann’s self-referential poem titled Evolution portrays the poet in the act of writing a poem about how insects are “good chemists,” using chemistry for defense, and, even more so, for attracting mates.

And I was in the middle
of telling the story of the western pine beetle,
which has an aggregation pheromone
calling all comers (of that species).
The pheromone has three components:
one from the male, frontalin,
exo-brevicomin wafted by the female
and (ingenious) abundant
pitch-smelling myrcene
from the host pine.

These lines, in language somewhat reminiscent of a scientific article, albeit with a touch of poetry, describe the complex, precise chemical formula that has evolved for the purpose of propagating the pine beetle.  But the poet and, indeed, the poem he originally drafted are undone, in part, by wild flowers he’d brought into the house and placed in a vase next to the poem.  This flora distracts him from the poem and he observes - 

The sun’s warmth had burst some of the pods,
which had fallen on the draft
(the words were lost in the sun) . . . .

The shadows from the wild flower bouquet lie across his draft deflecting him still further from his original poem, and . . .

Then I saw you walking on the hill.

The poem we have in hand (as I read it) tells us that, whatever wildly wonderful brew of forces that have evolved to attract members of our species to one another, it cannot be deconstructed into an intricate chemical formula, because it’s a quixotic blend of happenstance, the moment, idle musing, light and shadow.

Oh, I should add that Hoffmann is a Nobel Laureate in Chemistry (1981).  The science is as real as the poetry.

(The autobiography Hoffmann submitted to the Nobel Foundation is fascinating; the addendum from 1992 includes some reflection on the relationship of science and poetry.  Hoffmann has made a generous selection of his poetry available on the web.)

Mackay’s second category of scientific poem is the much less populated one consisting of poems in which science is the subject.

Mackay mostly limits this category to recent scientist who write poetry about science.  That's perhaps the safest route since, for older texts, much depends upon what one considers science.  Nevertheless, I'd argue that poems in this group have a very old and distinguished pedigree.  Renowned information scientist Eugene Garfield, in one of his Current Contents columns (which put me on to Mackay in the first place), observes that, in roughly 60 BCE, the Roman poet Lucretius (ca. 99 BCE – ca. 55 BCE) composed De Rerum Natura or On the Nature of Things, “the most extensive description of nature of its time.”  This was the "science of his day."

The poem deals with human nature and religion, but in large part it is a commentary on atomic theory, meteorology, astronomy, the origin of life, and the mechanics of perception.  (The Poetry-Science Connection, July 18, 1983.)

Even the limited amount of this epic poem that I’ve read shows me quite clearly how consonant much of it is with what is known now about the physical world, about the composition of natural objects and the conserving cycles that dominate nature.  A minor example will suffice.  A passage that waxes lyrical about new birth concludes with an observation about fertile death.

Hence the young scamper on their weakling joints
Along the tender herbs, fresh hearts afrisk
With warm new milk.  Thus naught of what so seems
Perishes utterly, since Nature ever
Upbuilds one thing from other, suffering naught
To come to birth but through some other’s death.
(Book I, Substance is Eternal, in the 1916 translation by William Ellery Leonard.)

But I’m reluctant to call it prescient because I don’t know what Lucretius really meant by the terms he used (well, those that I've read in translation).

Still, I agree with Garfield and think Lucretius counts.  Among the other notable scientific poems of past ages that I’d include in this group, is The Temple of Nature; The Origin of Society by Erasmus Darwin (1731 – 1802), a long poem (published posthumously) expounding this Darwin’s views on evolution.

I’ve recently come across a poem that might constitute a third category of scientific poetry – in this category, the poem isn’t ABOUT science, it appears that it IS science.  Or, put another way, the scientist appears to have written the poetry as an integral part of doing science.

Humphry Davy (1778-1829) is a central figure in biographer Richard Holmes’ award-winning book titled The Age of Wonder:  How the Romantic Generation Discovered the Beauty and Terror of Science (2008).  Davy made significant contributions to chemistry in this fecund period for the arts and sciences.  During the Romantic Age, the arts, particularly poetry, and science seemed twinned, practitioners of each were often one and the same, or, at least, close collaborators.  So, it’s not surprising that the chemist Davy was also a poet.

Very early in his career, Davy experimented with the effects of different gases on the human body and mind.  Indeed, the body and mind on which he experimented were often his own.  When sessions with carbon monoxide proved nearly fatal, he wisely tried a different gas, nitrous oxide, with categorically different and addicting results.  As part of his research, Davy used poetry to capture the essence of a gas high.  In a poem titled On Breathing Nitrous Oxide, he wrote

Yet is my cheek with rosy blushes warm
Yet are my eyes with sparkling lustre filled
Yet is my mouth replete with murmuring sound

Though Holmes dismisses the poem as “very bad verse,” he calls it "a form of scientific data," suggesting to me that it should be considered part of Davy's effort to immediately record what he'd experienced (p. 260).  Holmes posits that it provided “surprisingly precise physiological information” of the gas’ impact from sexual arousal to flushed cheeks, from hallucinations to a sense of physical prowess.

Reflecting the shared worlds of poetry and science in this period, Davy proved an admirable host for nitrous oxide sampling sessions, inviting such friends as the poets Robert Southey and Samuel Taylor Coleridge.  Not unexpectedly, Coleridge, who was deeply into opium, was not as moved as others.  Holmes writes, “In fact Coleridge’s accounts of his reactions to the gas seem oddly prosaic.”  (p. 267)

One might expect that the two poems on ostracodes and foraminifera that I found nestled in scientific articles might fit into this third category, as examples of the scientist doing science through poetry.  But, I think not.

I’m not sure where they belong, perhaps yet another category.  They speak to no truths about the human condition, and their subject is hardly science, though it has the appropriate patina.  Because these are not free-standing poems, their context – scientific journals – is all important and seems to dictate that they be played for . . . laughs.  Indeed, they are trivial.  That said, I did enjoy the poems and their articles, and it’s pretty clear the authors had fun writing them.

The first article, titled The Odds on “Ode” in Ostracode, or the Omicron and Omega of Chancy Spelling, appeared in the Journal of Paleontology (November, 1961) and tackles that most fundamental of issues for those who work with ostracodes –

Should the common name of these little crustaceans be spelled ostracode or ostracod (with appropriately different pronunciations)?

Paleontologist Richard H. Benson argues in this piece, from carefully assembled and footnoted etymological evidence regarding the use of the two terms, that ostracode is much the preferred.  He concludes with his Ode to Ostracode which in doggerel sums up his preceding detailed analysis.  The first two verses capture the essential geopolitical struggle over the spelling of the name.

In celebration of Oxford’s mode,
Most Americans spell it “ostracode.”

The Britisher’s closer proximity to God
Causes him to spell it “ostracod.”

The poem draws other nationalities into the fight, but notes that it’s of little consequence to most of the world.  Benson concludes the poetic effort with

I end this ode with a short delighter;
Both may be right, but one is righter!

The second of these poems appears in What Should We Call The Foraminifera?, a footnoted piece by Jere H. Lipps, Kenneth L. Finger, and Sally E. Walker, that appeared in the October, 2011, issue of the Journal of Foraminiferal Research.  Sally Walker is the designated poet in the group.  Her poem, titled Protist Protest, begins

Little protists of the sea
How do we treat thee?
As foraminifers, Oh wee beasties of the sea?
Or, shall it be, foraminifera
for the plural or the singular?

And ends with - 

Please, please tell me Dr. Foram Man or M’am,
Is it –minifer, -minifera, or –miniferan?

It would have pained me to end this post with such verse, so I wont.

As a lover of the fossil shells left us by gastropods, I am particularly taken with Roald Hoffmann’s poem Malacology, a dialogue about finding the universal in the quotidian, which finishes the whirling pattern it traces down the page with these lines arrayed in this fashion - 

But a snail –
            won’t it matter
                        it’s so glan-
                                    dular, all its
                                                            on display?

                        That’s what I
            said from the
            the world is
                        in a snail.

Tuesday, November 27, 2012

Richard Suter's Legacy

Yes, I must admit, and you are forewarned, that this is the third post in a row that in some fashion concerns mounting microscopic specimens on slides.  My apologies.

When poorly shredded records from the Nassau County Police Department somehow found their way into the confetti used in Macy’s Thanksgiving Day parade in New York City, bits of readable personal data literally rained down from the sky.  (Abby Rogers, Business Insider, November 26, 2012.)  How symbolic.  We are awash in information about people living today, much in print, much, much more in digital formats.

It's ironic that the capacity of the web to amass information about any one of us appalls me, yet I thoroughly enjoy its capacity to pull together the traces of lives lived out decades and centuries ago.  As a consequence, we do know something about the life of teacher and “microscopist” Richard Suter (1864 – 1955).  There are bits and pieces in the digital records, though much of the narrative is marked by gaps.  Nevertheless, it is a story salvaged by the marvelous legacy he left.  Peter B. Paisley, author of many superb articles detailing the history of British microscopy and, in particular, those who created slides with mounted specimens, has marshaled much of what is available about Richard Suter in a piece titled Those Other Suter Slides (Micscape Magazine, June 2010.)  I have relied principally on Paisley for the Suter family history that appears below.

Paisley includes Suter among the “well documented mounting family industries," but that may be because the record is poor for many other such enterprises.  (William Barwell Turner (1845-1917):  Life, Research and Business in Leeds, Micscape Magazine, September 2011.)

Suter was born in India in the city of Secuderabad in 1864 to Ann and Richard Suter, Sr., the latter presumably in the British Army at the time.  Paisley notes that the young family was back in England no later than 1871, living in inner London.  The growing family moved to No. 5 Highweek Road, Tottenham, some time after 1881.  Richard, Jr. had trained and worked as a school teacher, but the 1901 Census lists him as a “microscopist.”  He devoted much of his life to mounting and selling microscope slides, as well as the sale and exchange of microscopes and related items.  The enterprise was run out of the Suter home at No. 5 Highweek and subsequently No. 10.

There is no question that Suter’s interests ranged widely through natural history, presumably often with an eye to what would sell.  Consider the ads he posted in the Exchanges column of the monthly Hardwicke’s Science-Gossip:  An Illustrated Medium of Interchange and Gossip for Students and Lovers of Nature.  Based on those that ran in 1890 (Volume XXVI), he offered “choice” mounted slides of such objects as diatoms, parasites, and anatomical material in exchange for many different items including unmounted microscopic material, foreign butterflies, foreign shells, books about shells, stamps, books about microscopes, and “anything interesting.”  He also offered, in exchange, “rare British marine shells.”

In 1890, when Suter lived at No. 5 Highweek Road running this business out of the family home was probably no small undertaking.  But, by the end of the decade, when the family was in No. 10, I suspect the business posed even greater logistical challenges for the household.  In the December 10, 1898, issue of the Pharmaceutical Journal, Suter ran an ad announcing the availability of “50,000 Choicest Microscopical Objects” for sale!

Of course, one can pack a lot of microscopic objects into a small space, but not microscopes and cabinets, and mounting specimens on microscope slides in crowded conditions is asking for trouble.  Brian Bracegirdle (Microscopical Mounts and Mounters, 1998) comments on the quarters occupied by the Suter household and Suter business.

If one ever saw 10 Highweek Road, it was to wonder at how all this could ever have been produced and stored, while he was living with his sister and her family!  (p. 89-90)

"If one ever saw 10 Highweek Road" - I looked up the road in a 1900 map of London.  A short, very short stretch of road, marked with a black arrow in the image below from “Geographia” Authentic Atlas and Guide to London and Suburbs (1900, p. 16).

When I tried to make a virtual visit using Google Maps to Highweek Road, I found myself stymied, much as Paisley recounts in his article.  Sadly, it is no more, this trace of Suter is gone, victim to a housing development and the redirection of Stonebridge Road into a dead end.  Seemingly it incorporated Highweek in the process.

Thankfully, Suter left a legacy that, despite its inherent fragility, is still with us today - his prepared microscope slides.  Glass, microscopic specimens, and glue – not a combination with a very long half life.  Simply amazing that so many have survived (of course, he produced a multitude).  They are studied and enjoyed today much as they were a century ago, and they are scrutinized for clues about the man and his craft.

The very, very small part of that legacy in my possession is pictured below.  I’ll be generous and suggest it may be approaching, if not already passed, its centennial.  It’s a product of that crowded household at No. 10 Highweek Road.

On it, Suter arranged the tests (shells) from six small diatoms spoke-like around a single, slightly larger test.  This slide presents a simple radial arrangement of diatoms, a totally appropriate design given that these shells all come from a radially symmetrical kind of diatom (called Centrales).  The arrangement is pictured below.  (My apologies.  Photographing microfossils is an art that eludes me.)

Diatoms are single-celled photosynthetic protists that live inside and around a shell comprised of a nested pair of siliceous valves.  This two-valved shell is also known as a frustule.  I don’t know whether complete frustules are mounted on this slide or just individual valves.  The label on the slide identifies these as Heliopelta leeuwenhoekii, a name accorded a “preliminary entry” in AlgaeBase, an online database with information on over 130,000 algae species.  It notes that this entry “has not been subject to full verification.”

I’d love to know where these shells came from, but the label on the slide provides no provenance and, alas, the maker has long since left the scene.

Wednesday, November 14, 2012

Gorblimey! A Butterfly House!

The word gorblimey (also gor-blimey or gor blimey) originated in Britain in the late 19th century as a vulgar play on the oath “God blind me.”  According to the Oxford Dictionary of English, when used as an exclamation, it’s “an expression of surprise or indignation.”  As an adjective, it means “vulgarly lower-class.”  Finally, the dictionary notes that, early in the 20th century, it characterized “unusual clothing.”  Eric Partridge’s A Dictionary of Slang and Unconventional English (8th edition, 2002) offers a somewhat tangled set of usages for this Cockney expression that has a recurrent focus on clothing (hats in particular) defying regulation (military), convention, or perhaps good taste.

I first came upon the word only recently, in a description of the ways in which, since the 19th century, the shells (or tests) of diatoms have been arranged and mounted on microscope slides.  Diatoms, photosynthetic single-celled plankton, generate a breathtaking array of very small, geometrically shaped shells.  Brian Bracegirdle, in his marvelous guide to the (primarily British) world of mounted microscope slides (Microscopical Mounts and Mounters (1998)), notes that “prepared [diatom] tests . . . have been an object of fascination to English microscopists for well over a century.”  (p. 31)  Mounted diatoms have been put to practical and scientific uses – at times in the 19th century, they were employed to test the resolution of the objective lenses of microscopes.  Back then, as well as now, slides with mounted diatoms aided in the identification of diatom species or exploration of diatom diversity.  “Or they can be arranged,” Bracegirdle writes, “as pretty patterns/pictures for either reflected or transmitted illumination, to produce a gor-blimey effect.”  (p. 31)

I’m not sure how Bracegirdle is using gor-blimey in this instance.  Is the effect produced by these arrangements of diatoms vulgar?  Or, is this an effect sparking amazement?  Regardless, when I use gorblimey in this post, I intend it as an exclamation of surprise, the kind of oath I blurt out when I come upon something startling or unexpected, perhaps good (say, a particularly sweet sunset) or perhaps not so good (another day without electricity).

Fanciful arrangements of natural history specimens distress some folks.  In my previous post, I highlighted a microscope slide with an amazing bit of artwork made of fossil foraminifera shells, mounted by Arthur Earland in 1912 as a Christmas gift for Edward Heron-Allen.  In the first decades of the 20th century, Earland and Heron-Allen were among the preeminent experts on foraminifera (single-celled protists).

Michael Hesemann, who runs the highly recommended project website, offered a thoughtful comment on my post in which he criticizes the making of “nice images and arrangements” out of specimens, suggesting it was a 19th century sort of impulse.  He posits that we should “respect nature as it is,” and recognize the importance of these specimens and the evolutionary story they convey which “goes far beyond mere man-made harmony” and surface beauty.

Perhaps I was too dismissive of this point in the response I posted.  Despite how intricate and, yes, beautiful, some artful arrangements of mounted micro specimens can be, I’m more and more inclined to believe they do trivialize the objects of which they are made.  The test is, do they engage the viewer into going beyond the shine and flash, and discovering the science behind them?  I suspect mostly the responses don’t get beyond, “Gorblimey!”

It’s a challenging question to ask of displays, exhibits, or activities involving natural history.  Do they respect or trivialize the objects?  Where’s the education, where's the science?

In recent months, I had my first experiences with those walk-through exhibits of living butterflies and I loved them.  The Atlantis Long Island Aquarium & Exhibition Center in Riverhead, New York, has a butterfly house that captivated us for a couple of hours one weekday afternoon in September.  Given the few other visitors that day, we felt the butterflies were there for us alone.  Armed with pens and the butterfly house’s brochure listing 14 North American species and 18 exotic species (mostly from Asia), we went on a butterfly hunt throughout the exhibit, checking off species as they fluttered by or, as our search images developed, they slowly appeared in the foliage.  Magical.

The following identification of the butterflies shown in my montage above relies mostly on the Atlantis brochure, supplemented by some exploring of the web:

upper left corner – several examples of Paper Kite butterflies (Idea leuconoe)
upper right corner – a Scarlet Mormon butterfly (Papilion rumanzovia)
center middle – a Glasswinged butterfly (perhaps Greta oto, but I’m not sure)
center, a bit lower – a Common Blue Morpho butterfly (Morpho peleides), appears smaller than is
middle left – several examples of Great Egg Fly butterflies (Hypolimnas bolina)
middle right – a Tawny Owl butterfly (Caligo memnon) showing the top of its wings
bottom left – a Polymnia Tigerwing butterfly (Mechanitis polymnia)
bottom right – more Tawny Owl butterflies (Caligo memnon) with folded wings

When one of the exhibit’s curators wandered through and willingly became our guide for much of the afternoon, some of what’s known as the butterfly house industry came into view.  That the array of butterflies featured in the exhibit’s brochure did not fully match the species seen on this day reflects the fact that the stock available from his suppliers is dependent upon myriad factors, including the time of year.  He described a visit to check up on one source of his stock, a butterfly farm in Florida, and mentioned restrictions that limit him to the role of exhibitor, not breeder (for instance, he cannot include flora essential for butterfly propagation in his exhibit).

In a carefully crafted overview and critique of the butterfly house industry, ecologist Michael Boppré and etymologist R.I. Vane-Wright have identified its key components – a far reaching constellation of breeders, suppliers, exhibitors (exhibits), and visitors.  (The Butterfly House Industry:  Conservation Risks and Education Opportunities, Conservation and Society, Volume 10, Number 3, 2012.)  The authors sound an alarm about key aspects of the industry while simultaneously offering a roadmap to an environmentally sustainable and scientifically supportable future.  The discussion below draws from their article.

Though elements of this industry began centuries ago with the trading and collecting of insects, it’s really two recent technological advancements that have made all the difference – instantaneous communication via cell phones and the internet, and the creation of a rapid worldwide delivery system.  These have made it possible to stock and restock butterfly houses within the brief lifespan of butterflies.  It’s a growth industry – butterfly houses and large scale butterfly gardens exist in over 50 countries, the estimated money changing hands with the purchase of butterfly pupae is between $10 and $20 million annually, and more than 40 million people each year visit these houses and gardens.

But it’s a largely unregulated industry that, unless it takes appropriate steps, poses serious risks to the environment and to butterflies.  The comforting vision of myriad mom and pop operations in developing countries generating needed income by securing butterfly pupae while protecting the environment doesn’t hold up, according to Boppré and Vane-Wright.  Actually, small scale breeders who gather larvae and pupae in the wild, or who capture females butterflies in the wild and ship off the generated pupae (practices known collectively as rearing) threaten the continued existence of local butterfly populations, particularly uncommon or rare species.  The sustainable breeding model Boppré and Vane-Wright advocate is large scale, of a size sufficient to cater to the worldwide market and afford to engage in practices that conserve and support local butterfly populations and environment.  This model involves reliance on locally obtained specimens, the periodic release of adults back into the wild, and the periodic refreshing of the breeding stock with individuals from the wild.  These enterprises (breeders and suppliers), they argue, should limit themselves to “industry-suitable, common species native to their own area of operation” and eschew shipment of species to other, potentially compatible regions (e.g., sending tropical butterflies to other tropical regions). (p. 294)

The deliberate or accidental release of butterfly species into the wild by any participants in the industry may spell disaster for biodiversity and for the environment.  “The biological basis of the threat is due to the fact that all butterflies, like the vast majority of organisms, have more or less restricted natural ranges caused by the interaction of history (phylogenesis) and ecology.” (p. 290)  If alien species find a hospitable niche in the new environment, they may disrupt local populations.  I would visit a pox upon that element in the butterfly trade that enables the mass release of butterflies at special ceremonies such as weddings (talk about trivializing!).

Boppré and Vane-Wright posit that, because butterfly species abound with subspecies the possibility that breeding operations will spur genetic mixing is high.  The danger is that breeders will bring together genetically different subspecies (made easier by the fact that genetic diversity is not necessarily manifested in physical differences) that otherwise would remain physically separated in the wild.  If they crossbreed successfully, all bets are off.  “With respect to hybridization, rearing closely related butterflies in an artificial, closed environment represents an uncontrolled experiment.”  (p. 293)

Unless carefully controlled, the commerce in butterfly pupae can also move parasites and diseases into new areas and into populations with no natural defenses with unknown consequences.

It’s not all doom and gloom.  Despite the ecological dangers inherent in the butterfly house industry, it represents an enormous opportunity to foster greater environmental awareness and conservation activism in the millions of visitors who walk through these exhibits each year.  This is the opportunity to move the butterfly house experience from entertainment that trivializes or disrespects these insects to an experience that informs and energizes the visitors for the benefit of the insect.

Boppré and Vane-Wright assert, “For butterfly houses to justify the environmental risks they present, we believe they must engage in effective environmental education . . . .”  (p. 296)  They should take it as their mission to educate visitors about natural systems and about the threats to  butterflies’ habitat.  They should feature outdoor butterfly gardens to support local butterfly populations and to encourage the planting of these gardens.

Frankly, the educational challenge is enormous.  “Although there are rare examples of good educational practice, the educational offerings presented by most butterfly houses are insufficient, misleading, incorrect, or even lacking altogether . . . .”  (p. 296)  In addition to the butterfly house in Riverhead, New York, I also recently visited the Butterfly Pavilion at the Smithsonian’s National Museum of Natural History.  Its educational trappings are more apparent, but, for the life of me, I cannot remember much of what either exhibit may have intended that I learn about the life history of butterflies or the natural systems of which they are a part.  And therein lies the real challenge.

Assume, for the moment, that a butterfly house fully embraces this mission and features clear, accessible displays or activities that explore the ecological role played by butterflies, the threats to their survival, the nature of the enterprises supplying the butterflies on display, the dangers inherent in the butterfly house industry and steps taken to address them, and the positive roles that visitors might take to support local and foreign butterfly species and conservation in general – would any of that sink in?  Would there be room or time for the butterflies?  Perhaps education would be better served by targeting one or two critical messages.  I was struck by the fact that the Natural History Museum's butterfly house did not, as a matter of course, provide me with any handouts addressing even one of these concerns.  Something as simple as “here’s what you might do to help butterflies in your local community” would be a start.  And that's where the Atlantis butterfly house in Riverhead has taken its first step - its guide to the species on exhibit provides a brief "Butterfly Gardening Hints & Tips."  Though, to its credit, the Natural History Museum does have an outdoor Butterfly Habitat Garden along one side of the building.

The narrowing and targeting of the messages and the fashioning of the educational efforts may be less of a hurdle than simply capturing visitors’ attention.  The very connection that draws people to these exhibits and so moves them as they witness the free flying butterflies may preclude most from attending to any of these educational messages while in the butterfly house.  Besides some take-away material to be read later, away from the butterflies, I don’t quite know how to get over this barrier.  I know from personal experience that, once in the butterfly house, we are spellbound by, and only have eyes for, the beauty around us.


Sunday, October 28, 2012

Mounting Microfossils ~ Forams and Glue, Art and Polymaths

In which the blogger exudes enthusiasm for mounting microfossils on slides, and finds, amid the shells and glue, art and polymaths (though he stretches the definition of the latter).
Science and Art

It’s a marriage of science and art.  Mounting the tests or shells of microorganisms on microscope slides is an integral part of safeguarding, organizing, cataloguing, and researching these tiny specimens (generally on the order of half a millimeter or smaller).  But there’s an aesthetic appeal for me in this as well.  Pictured below is a slide on which I’m beginning to categorize some of the foraminifera fossil shells that I’ve found in a sample of Jurassic material (Oxford Clay from Yaxley, England).

Given the gaping holes in my knowledge of these single-celled protozoa and the shells they create, I’m really not sure whether the groups I’m creating are species specific to any degree, or whether I’m simply discriminating among specimens of the same species on the basis of irrelevant physical characteristics or vague traces of the preservation process.  Despite how inchoate this is, I find even this slide to be visually intriguing.

As slides accommodate more and more specimens, their visual appeal can grow markedly.  Case in point – the two slides shown below, prepared by Karl-Otto Bock, contain many shells of recent (not fossils) foraminifera from two locations – a beach at Malia, Crete, Greece (first, very crowded picture) and the ocean floor in the Hebridian Slope in the North Atlantic (second, sparser picture).

(The images of both slides were downloaded from Michael Hesemann’s website of the, and are reproduced under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany License.  The represents the work of scientific amateurs and professionals dedicated to promoting knowledge of, and research about, foraminifera – a rich and very useful site.)

Bock has grouped the foram shells by species on these slides.  How the specimens are arranged within each cell, how many to place in a cell, which species are placed near to each other, where the species with the most bizarre structures are settled, are among the many choices to be made in this process.  Even if Bock gave no thought to the aesthetic effect of the arrangements he’s creating, surely there is one.  And the opportunity for a touch of humor is there – notice the #10 cell in the Crete slide (the first slide) with a foram placed in the 0.  (On the website, clicking on individual cells in a slide brings up information about that species.  Very cool.)

This is painstaking work.  Manipulating the small shells with the fine hairs of a wet brush and positioning and affixing them just so demands a steady hand and an inordinate amount of patience.  There’s luck involved as well given the propensity of the specimens to “jump” if touched with a brush that’s not wet enough.  If one of these escapees manages to end up off the slide and out of the tray in which the slide might be resting, good luck finding it again.

Occupying a special place among mounters of microfossils are Arthur Earland (1866 – 1958) and Edward Heron-Allen (1861 – 1943).  Though amateurs in a strict sense of that term, both men were leading figures for three decades in the study of foraminifera, collaborating on many significant studies.  Among their notable efforts is the study of the foraminifera brought back from Robert Falcon Scott’s star-crossed expedition to Antarctica (1910 – 1912) (Protozoa, Part II.  Foraminifera, British Museum, Volume VI, No. 2, 1922).

Earland, who spent his working life in the Post Office Savings Bank Department, was a “Civil Servant who worked at Forams as a relief from the monotony of his job.”  This is Earland’s own description of himself, if I correctly read his obituary in the Journal of the Royal Microscopical Society, September – November, 1957.  In 1954, he informally estimated that the new foram taxa identified by the Earland/Heron-Allen collaboration included at least 2 families, 1 sub-family, 19 genera, 133 species, and 64 varieties.  The Royal Microscopical Society obituary concludes, "He leaves . . . the reputation of a forthright man of sterling character, the last of the nineteenth century masters of the Foraminifera in Britain."  Perhaps it’s only appropriate that there’s precious little biographical information on the web about this most self-effacing man.

Human Polymath

In contrast, Heron-Allen continues to captivate nearly 70 years after his death.  (The brief portrait of Heron-Allen which follows is based largely on information in R.B. Russell's Short Biography of Edward Heron-Allen appearing on the Heron-Allen Society website, and Edward Heron-Allen:  the Man and his Scientific Library, by Clive Jones which was published in the Winter 2004 issue of Set in Stone, the newsletter of the Palaeontology Department of the Natural History Museum, London.)

Russell asserts that, despite the man's many diverse areas of endeavor, “[r]ather than a dilettante, Heron-Allen is better described as a polymath.”  Heron-Allen trained and worked, at times, as a lawyer, but that was the least of it.  His scientific work, including his collaborations with Earland, was so highly regarded that he was elected in 1919 to the Royal Society.  He also apprenticed himself to one of the period’s foremost violin makers, made violins, and wrote extensively on them.  Among his books was the popular Violin-Making:  As It Was and Is (1914).  He also studied languages, publishing several translations of Persian literary works, including one of The Rubaiyat of Omar Kahyyam.  In the 1880s, Heron-Allen dedicated himself to palmistry or cheirosophy (also spelled chiromancy).  On this, too, he published successfully and then undertook a triumphal tour of the United States.

He turned to fiction; among his novels was a light romantic novel which he titled The Romance of a Quiet Watering-Place (Being the Unpremeditated Confessions of a not altogether frivolous Girl) and published in 1888 under the pseudonym Nora Helen Warddel (an anagram of his name).  Later, as Christopher Blayre, he wrote tales of the supernatural, such as The Purple Sapphire.

I would note that, perhaps for good reason, The Purple Sapphire, which is tale of a cursed gem stone purloined from a Hindu statue during the Indian mutiny in the 1850s, has the ring of truth to it.  The website of the Natural History Museum describes (7th slide at this link) a purple sapphire in its collection, and on display in its “vault,” as having been looted during the Indian mutiny and associated with misfortune for all of its owners since.  According to NHM, the sapphire’s final owner, Edward Heron-Allen, deemed it cursed and locked it away in an bank.  After his death, his daughter gave it to the NHM.  An appropriate dénouement, given that in the short story, the stone’s final resting place is the museum at the fictitious University of Cosmopoli.

One special aspect of the Earland and Heron-Allen collaboration was their Christmas slides.  Giles Miller, the NHM Curator of Micropalaeontology, describes in a post (Microfossil Christmas Cards) on his always fascinating blog that, at Christmastime, Earland and Heron-Allen exchanged microscope slides on which they had mounted foraminifera fossils.  The practice continued until the early 1930s when their friendship ended.  Pictured below is a slide from Christmas, 1912.

Simply amazing.  Clearly written in forams is “AE XMAS 1912.”  When I first saw the photograph of this slide, I was stunned first by the startling realization that these men had beautiful fossil foram tests in such abundance that they could indulge in this activity, and then by the time and patience required to render this piece of art.

Not shown in the photograph are the handwritten notes on the slide:  “Xmas 1912” and “Prosit!  AE.”  (They can been seen at this link at the NHM.)  I believe this particular slide was a gift from Earland to Heron-Allen.  The picture is copyrighted by The Natural History Museum, London, and is used with permission.

Botanical Polymath

But Heron-Allen isn’t the only polymath I have stumbled upon as I pursue my interest in mounting microfossils on slides.   I have found what I can only term a botanical polymath - gum tragacanth.  The adhesive I use to affix microfossils to slides is a solution of water and gum tragacanth.  When I began to work with microfossils on my own, I followed the lead of paleobiologists Howard Armstrong and Martin Brasier who, in their Microfossils (2nd edition, 2005) advise,
Adhesion of microfossils is improved by brushing the slide’s surface beforehand with a weak solution of Gum Tragacanth to which a drop of Clove Oil has been added (to reduce fungal growth).  (p. 279)
When the gum tragacanth solution dries on the slide, it is ready to receive individual microfossils.  Transferring a fossil to the slide with a slightly wet brush activates the water-soluble glue which will hold the fossil in place when it dries.  Of course, being water-soluble, the glue easily releases the microfossil when moistened.  Whether the clove oil will actually retard fungal growth remains to be seen, but there’s a delightful scent released as my wet brush touches the dried solution.

Over the years, many different adhesives have been suggested for microfossils, but the gum tragacanth solution appears to have remained among the favorites, cited often in books and articles describing working with microscopes to view microorganisms.  For instance, in 1922, Arthur Earland wrote
The best fixative for mounting is gum tragacanth, which is almost invisible when dry, being quite devoid of the objectionable glaze which characterizes gum arabic.  It is also much less subject to variations of moisture than gum arabic which alternately contracts and expands with changes of weather and often fractures delicate forms.  Powdered gum tragacanth should be used in the preparation of mucilage.  (Collecting and Preparing Foraminifera, in Modern Microscopy:  A Handbook for Beginners and Students, edited by M.I. Cross et. al., p. 263.)
Still earlier, in 1859, William Lowndes Notcutt recommended that opaque objects, which required the focusing of an external light source, be mounted on blackened slides with “mucilage of tragacanth, also previously mixed with black.”  (A Handbook of the Microscope and Microscopic Objects, p. 28)

Gum tragacanth is the dried sap from Astragalus gummifer, a plant known by various common names such as goat’s-thorn and tragacanth milk-vetch.  The plant is a small, thorny, evergreen shrub, native to the semiarid grasslands and dry mountainous areas of Western Asia, including Iran, Lebanon, Syria, and Turkey.

This illustration is taken from Medicinal Plants, Being Descriptions With Original Figures of the Principal Plants Employed in Medicine and An Account of the Characters, Properties, and Uses of Their Parts and Products of Medicinal Value, by Robert Bentley and Henry Trimen, Volume II, 1880, entry 73.

Gum tragacanth has a extensive history, having been described, according to biochemist Amos Nussinovitch, at least as early as 300 years before the beginning of the Common Era.  (Plant Gum Exudates of the World, 2009, p. 55.)  It has long been part of Materia Medica, the study of pharmaceutical chemistry, particularly those substances derived from plants.

Bentley and Trimen describe how the gum naturally emanates from breaks in the plant’s stem, in a flow likened by one authority they cite to a “worm.”  The harvesting of quality gum tragacanth involves digging around the base of the stem, making an incision, and collecting and drying the gum that streams from that cut.  If properly prepared, the material collected from these incisions dries in white flakes.

Chemically, the gum is an edible, complex, acidic polysaccharide.  Agricultural biochemist Mark Dreher explains that
Tragacanth is composed of a mixture of polysaccharides:  traganthic acid, a water-insoluble component, which confers water-swelling properties to the gum; and arabinogalactan, a water-soluble polymer that gives the gum solubility.  (Food Sources and Uses of Dietary Fiber in Complex Carbohydrates, edited by Susan Sungsoo Cho, et al., 1999, p. 347.)
In solution, it is very viscous or gel-like.

Gum tragacanth has been exploited for centuries for its thickening, binding, water absorbing, and stabilizing attributes.  It is incredibly versatile; I learn of new uses in nearly every additional source I consult.  At the same time, the volatility of the part of the world from which it originates, has led to the search for alternatives.  (I must also admit that I don't know if other plant gums, such as gum arabic, are equally versatile.)

Here, then, are just some of the applications of gum tragacanth.  It has been added to many, many foods, including salad dressings, sauces and gravies, ice cream, sherbet, chocolate milk, processed cheese and cheese spread, syrups, catsup, and candy, particularly chewy candies.

[Later edit:  With the passing of superstorm Sandy along the east coast of the U.S., I was finally able to wander the aisles of my local grocery store and gauge the extent to which alternatives have displaced gum tragacanth in foods.  Apparently, it's been a thorough overthrow.  I discovered no mention of gum tragacanth for foods in which it might have been used in the past.  Xanthan gum appears fairly frequently, a gum that offers a fascinating story on its own, being the byproduct of a fermentation process involving certain strains of bacteria.]

Beyond food, gum tragacanth has been used as a laboratory culture medium; a digestive tract stimulant, treating both diarrhea and constipation; a treatment for tumors; burn dressings; a thickener for textile dyes, ink, water colors; a binder in paper manufacture; and, of course, glue (including the sealer for the final, outermost leaf in cigars).  It is also added to toothpaste, lotions, denture paste, and spermicidal jellies.  Given the last application, it’s probably appropriate that, for millennia, it has also been considered an aphrodisiac.

I must mention one final use of gum tragacanth.  Edward Heron-Allen noted, in Violin-Making:  As It Was And Is, that the gum has been an ingredient in the varnish applied to violins.

Interesting where forams and glue may take you.

Sources Used But Not Specifically Cited in This Post

David Julian McClements, Food Emulsions:  Principles, Practices, and Techniques, 2004.

Rebecca Johnson and Steven Foster, National Geographic Desk Reference to Nature’s Medicine, 2008.

Entry for Astragalus gummifer on the website of Plants For A Future.

Entry for A. gummifer on the Ecocrop website of the UN’s Food and Agriculture Organization.

Entry for A. gummifer on the U.S. Department of Agriculture’s Germplasm Resources Information Network website.

Entry for tragacanth on the WebMD website.

Thursday, October 11, 2012

Lingering Around and Shaking Things Up

An October week’s retreat to my summer cottage on the North Fork of Long Island, New York, shifted a small portion of my paleontological world.

It began when I went biking in the middle of the week and became convinced that, with the falling temperatures of the previous night, had come an invasion of body snatchers.  An invasion from Mr. Roger’s Planet.  Everyone I passed – jogger, biker, walker – old, young, middling – greeted me with a robust “Hello, neighbor!”  Well, more like “Hey,” “Hi,” “Hello,” “Morning.”  What had happened to the summer’s many pointed rejections of my overtures?  Had something transformed these aggressively isolated Homo sapiens into a community of greeters (and possibly huggers)?  I wondered if the coming of fall, and particularly the first cold snap, had signaled subliminally to the locals that anyone out and about now was one of them.  The summer invaders had, at long last, all gone home.  But little did they know that I was a lingerer, someone left over from those summer days.

I was still contemplating whether I had been enjoying a wave of overt friendliness under false pretenses when I parked my bike in the sand and went in search of shells.  I walked along one of the beaches that line the bays that separate the North and South Forks of this eastern end of the island.  The twin forks are shown in the map below, separated by various bays, Great Peconic, Little Peconic, Gardiners Bay, etc.

View Larger Map

The expected shells appeared, jingle shells, slipper shells, clams and a sprinkling of oyster drills.  Then I spotted a chalky white cusp of a shell, worn, with a scar.  (Pictured below.  The 3/4" line applies to the image of the interior of the shell and measures the distance from the posterior end to the anterior.)

I had seen this kind of shell before, just never here, and not of this time.  It’s a somewhat common shape among the fossil shells I've collected at the Calvert Cliffs from the Miocene Epoch (23.0 to 5.3 million years ago) – an ark shell – from the Arcidae family of shells.  A recent post features two fossil specimens of Anadara staminea, a much larger, more steeply arched, extinct member of this family.  [Later edit:  I should clarify.  I do know that there are many extant species in this family and many beaches where these shells are common.  On this particular beach, this shell appeared out of place.]

But this is Long Island.  Long Island, in my world, is among the “not-fossil” places, the product of glacier action toward the end of the Pleistocene Epoch (which ran from 2.6 million years ago to 11,700 years ago) that shaped the island and essentially plowed over rock formations that might yield fossils.  But I also would acknowledge that, despite my having dropped it into this category, the island is not totally bereft of fossils, though most of those very, very few that might be found are likely to be invaders from Connecticut, carried over by the glaciers.

I pocketed the shell and, back in the relative warmth of my cottage, consulted two volumes I had at hand:  Harald A. Rehder’s National Audubon Society Field Guide to North American Seashells (1981), and R. Tucker Abbott’s How to Know the American Marine Shells (1961, an aging paperback shedding its pages).

Shell guides are blunt instruments, generally ruling out candidates and only on occasion leaving me with just one species standing.  With these two guides, I rejected a number of ark shell candidates, relying mostly on such obvious physical attributes as the overall shape of the shell, placement and structure of hinge, and features of the umbo.  (The umbo is the beak-like projection that arches over the hinge.  Donald J. Borror, in his Dictionary of Word Roots and Combining Forms (1960), defines the Latin umbo as “a projecting knob; a shield.”  Curiously, the plural is umbones.)

Rehder steered me to the Ponderous Ark (Noetia ponderosa), but I hesitated to come to rest there because of two sources of serious doubt in the description – the size and the range.  My shell was less than an inch long; Rehder said N. ponderosa came in between 1 ½ to 2 ¾ inches.  The distributional range was described as from “Virginia to Florida and Texas.”  To be sure, neither size and range is necessarily dispositive for an identification.  Shell size is tricky given that it is age specific, and ranges defined in 1981 may have shifted in the warm decades since.

But when I read the concluding sentence of Rehder’s description, it was suddenly immaterial whether my shell was a Ponderous Ark or not.  There, in black and white, were words that nudged the continents of my paleontological world in a slightly new direction:
Fossil shells of this species are sometimes found on beaches as far north as southern Massachusetts; washed out from fossil beds, they are testimony that the waters in that area were once warmer.  (p. 672)
Fossils in the wash at the beaches in Massachusetts?  Perhaps even Long Island as well?  Was that possible?  I grabbed Abbott’s book and thumbed to his description of N. ponderosa (a page or two came loose as I did):
Fossil specimens are occasionally found on Nantucket, Massachusetts beaches.  (p. 133)
Not as encouraging, though still acknowledging a fossil connection.

So, what is the possibility of finding fossil shells on Long Island beaches?  I googled “Noetia ponderosa” and “fossil,” and found naturalist Susan J. Hewitt.  She took the lead in reshaping my paleontological reality, writing that the chances of collecting fossil shells on some Long Island beaches are actually quite good.
On some of the exposed sand beaches of the outer Atlantic coasts of New York and New Jersey, the beach drift can contain numerous fossil shells of bivalve and gastropod mollusks. . . . On the beaches that I am familiar with, on days when there is a lot of beach drift, there are usually lots of fossils present.  Sometimes fossil shells are nearly as common as fresh shells, and always they are mixed in with the fresh shells higgledy-piggledy in the drift lines.  (Fossils on the Beach, American Paleontologist, Summer, 2008, p. 12)
Simply amazing.  She plows through the narrow confines of species and locations that Abbott and Rehder had erected for the phenomenon.  In one spellbinding article, Hewitt released me from my paleontological exile on Long Island.  No longer do my summer journeys here have to cut me off from hunting fossils in the surf.

What’s the story behind these fossils?  They date as far back as the late stages of the Pleistocene Epoch, not very old compared to what I’m used to, but still old enough.  Importantly, these are fossil specimens of species that are mostly still with us today, though, such as in the case of the N. ponderosa, not necessarily living in the same geographic range in which they used to live.  More than 12,000 years ago, the Ponderous Ark’s range extended into these waters.

Hewitt cites an article by Thomas C. Gustavson (Paleotemperature Analysis of the Marine Pleistocene of Long Island, New York, and Nantucket Island, Massachusetts, Geological Society of America Bulletin, January, 1976) which shows that these various kinds of fossil shells are Pleistocene in origin, coming from species that lived in this area during a warmer interglacial period.

I haven’t read this piece by Gustavson (unfortunately, my local college connection wasn’t up to penetrating the paywall that the Geological Society of America puts up around its articles).  But, elsewhere, Gustavson has written about fossil finds on the eastern end of Long Island that reveal a fauna characteristic of warmer waters, waters of a temperature closer to those prevailing today from Virginia southward.  (A Warm-Water Pleistocene Fauna From the Gardiners Clay of Eastern Long Island, The Journal of Paleontology, May 1972.  This also hides behind a paywall, but it’s JSTOR and accessible to me.)

Though the specific material he worked with – Gardiners Clay – was found on the South Fork of Long Island, Gustavson mentions other research identifying fossiliferous Pleistocene sediments, including Gardiners Clay and Jacobs Sand, on Robins Island and Gardiners Island.  Both of these small islands are positioned very nicely in the middle of the waters that separate the twin forks of Long Island.  Not too much of a stretch to think that fossil shells on my beaches might have eroded out from those islands.

Hewitt goes on to make my life more complicated by explaining that some extant species that currently live off the Atlantic beaches are likely to be represented in the wash by both fossil and non-fossil shells.  This makes it all the more important to figure out how to tell fossil from non-fossil versions of specimens from the same species.  For instance, it’s a given that fossils will not have the periostracum (an organic layer that covers the shells of many mollusks, it’s the often dark material that seems stuck to the exterior of some shells found on the beach), nor will there be any trace of the actual ligament that once joined two valves together.  Further, bright colors will be gone.  Hewitt observes that “the fossil shells tend to be oddly discolored:  many are various dull and unnatural-looking shades of gray, but they can also be off-white, tan, or faintly rust-colored.”  She emphasizes that a fossil shell will be “opaque and extremely dull-looking, even in the interior of the shell (p. 12).”

These are all attributes I’ve come to expect of the shells I find in places where nearly every shell is a fossil.  When the mixture of shells may contain a healthy offering of non-fossil shells, these indicators will not always do the job of separating out the fossils.  Further, shells that are just somewhat old, on the order of decades or even a century or two, are likely to share many of these fossil-like attributes.  This wont be easy.

Hewitt points to the barrier islands off Atlantic coast beaches of New York and New Jersey, those “ancient, sand bars,” as the source of the fossils.  “Under the topsoil, these [barrier] islands consist of sand deposits of various ages: some old, some very old, and some ancient (p. 13).”  As these barrier islands erode and re-form, they expose “shells from the older, much older, and ancient deposits” and the waves do the rest, unleashing invaders who have lingered from another time and are now shaking things up for me.

Though my collecting is along the beaches between the North and South Forks of Long Island, not on the Atlantic beaches of the South Fork, I think I can still count on ocean currents and wave action to spread fossils my way from those barriers islands.  And, as I noted earlier, the islands between the forks could also offer up their fossils to my beaches.

One final question.  Who is Susan Hewitt?

Well, I really like her vita.  She is a dedicated, published, amateur naturalist who has studied mollusks for many years, recently as a field associate in the American Museum of Natural History’s Division of Invertebrate Zoology, and as a volunteer in the Museum’s Division of Paleontology.  (See the volunteer page for the Division of Paleontology of the American Museum of Natural History.)

This citizen-scientist calls herself “a naturalist in the British tradition.”  All very 19th century.  Appropriately, she seems to be a lingerer from another time.


At this stage, I’m not sure of the identity of the shell that helped precipitate this post.  I still think it might be a fossil Ponderous Ark, albeit very much on the small side.  But it may also be a Transverse Ark (Anadara transversa) which has a present-day range covering Long Island and which is typically smaller than the Ponderous Ark.  If a Transverse, this worn veteran of the seas could still be a fossil, or just old.

Of course, there's never a final question.  After consulting several other shell guides for North America's Atlantic coast, all of which suggest fossil N. ponderosa shells may appear on beaches in some places to the north of its current range, I wonder why none of them suggest that fossil shells from other species might be in the drift lines on the beach.

[Later edit:  There's another question that merited consideration in this post.  How does Hewitt distinguish between merely old shells and fossil shells?  It's a matter of how old.  She writes, ". . . these shells are considered fossils only because they are so extremely old . . . . (p. 12)"  It's an accepted distinction.  As paleontologist Donald Prothero notes in Bringing Fossil to Life (1998), the label fossil is applied to "many shells (particularly those of Pleistocene age) [that] still have their original shell material unaltered . . . . (p. 6)"]
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