Nobel Laureate John Mather and Me - A Review of The Very First Light

Earlier this year, I attended a talk by physicist John Mather which had the wonderfully ambitious title of From the Big Bang to Quantum Energy to Life.  Mather, who shared the Nobel Prize in Physics in 2006, did yeoman's work in keeping his remarks accessible to an audience of the interested, but not necessarily scientifically literate.  Given the breadth of the charge he'd set for himself, the work for which he won the Nobel Prize was just part of his sweeping survey.  With regard to that prize-winning endeavor, he was, as The Royal Swedish Academy of Sciences characterized it, a "driving force in the project" that conceptualized, designed, built, and put into orbit the Cosmic Background Explorer (COBE) satellite.  Launched in 1989, COBE gathered data that provided striking evidence for the Big Bang origin of the cosmos.  After COBE, Mather went on to lead the science team for the James Webb Space Telescope, a project he had proposed.

Given that this was to be my first encounter with a Nobel Laureate, I wanted to make it memorable.  I went in search of Mather's book about COBE titled The Very First Light:  The True Inside Story of the Scientific Journey Back to the Dawn of the Universe, co-written with author and reporter John Boslough (1996), thinking it might be fun to approach Mather and ask him to inscribe it.  Unfortunately I ran out of time and had to content myself with simply sitting in the audience, listening to his genial, though rapid-fire, talk.

Subsequently I bought a second hand copy of Mather's book from Thrift Books.  It turned out to be a great find in two remarkable ways.

The first significant reveal was that the book is quite engaging, offering an inside view of what it takes to do "big science" and explaining, in layman's terms, some of the cosmology involved.  After reading it, I decided to write the review which follows here.

Written in the first person, the book tells the COBE story from Mather's perspective.  It moves easily back and forth between explanations of the cosmological science which undergirded and prompted COBE, and the challenges that Mather and his colleagues faced and largely overcame in marshaling this big science project from conception to fruition.

As Mather tells it, central to COBE is what flowed from the accidental discovery in 1964 by Bell Labs scientists Robert W. Wilson and Arno A. Penzias of the cosmic microwave background radiation which, it appeared, fills the universe.  Proponents of the Big Bang believed that during the first 300,000 years of the universe, radiation from densely packed photons "dominated everything."  At that point, as the universe continued expanding and energy levels fell, radiation and matter separated, with gravity assuming a central role affecting matter.  This is the so-called "decoupling."  Meanwhile, the microwave radiation, the "afterglow" of the Big Bang, remained, steadily cooling.  (Discussions of these phenomena are spread throughout the book, particularly at p. 43-52, 113-114.)

As I understand it (and I probably don't) from Mather's account, the uniformity of the background microwave radiation was expected, given that it was hypothesized to have originated in what was in essence the "blackbody" of the universe in the early moments of the Big Bang when thermal equilibrium prevailed.  One of COBE's instruments (the one for which Mather was principal investigator) was designed and constructed to answer the question:   did the background radiation, indeed, have the telltale signals of having originated in a blackbody?  If it did, then here would be proof of the reality of the Big Bang origins of the cosmos.

But the uniformity of the background radiation was troubling, given the present structure of the universe.  This raised another key question for COBE, for which a second instrument was constructed:  is there evidence of "anistropy" in the uniform background radiation (that is, minute differences in temperature in different directions in the universe)?  If such perturbations were found, it might help show that the seeds for the non-uniformity that the universe now exhibits (galaxies, stars, planets, us, etc.) were present shortly after the Big Bang.  This would be, according to Mather, "the mysterious missing link in the story of the universe's evolution."  (p. 269.)

COBE was a resounding success, answering both of those questions dramatically in the affirmative.  As John Mather said in his Nobel Lecture, From the Big Bang to the Nobel Prize and Beyond (December 8, 2006):

The COBE mission, started in an era when slide rules were common and aerospace designers used pencils and large sheets of paper, led to a revolution in our understanding of the universe.  It confirmed the Big Bang theory, and discovered the primordial density fluctuations that formed the large-scale structure of the universe. 

The book offers an insider's look at how science is done.  It describes the interplay of theoretical physics and experimental physics, with the former creating theory and the latter generating evidence proving or disproving theory.  It makes clear that science moves forward in fits and starts, with misses and near misses, with accidental discoveries and overlooked discoveries that are re-discovered.

As already noted, the story told here is one of big science.  The effort to gather the evidence for which the COBE project was designed required a huge investment in people, money, and time.  In the end, COBE demanded the contributions of an estimated 1,600 individuals, the expenditure of between $350 and $400 million (including the cost of the rocket), and about 15 years of time.  It necessitated selecting, organizing, and directing this staff; securing, managing, and defending the large budget; navigating the labyrinth of government and private contracting; and playing politics through the recruitment and nurturing of advocates in high places.

Nothing small about it and, from Mather's perspective, some of it wasn't enjoyable and was particularly challenging for a young scientist.  He notes that he was accused of being too young and immature to shoulder his responsibilities.  (p. 126.)  He endures the bureaucratic or the corporate side of all of it, commenting at one point that "soon I would be getting my feet wet in what was to me the slick-bottomed pond of the business world."  (p. 140.)

The project was often one step away from being cancelled.  One of the events that nearly undid COBE was the Challenger disaster.  The satellite, initially designed to be carried into orbit by rocket, was then constructed to be deployed from a shuttle.   With the grounding of the shuttle program, it was unclear whether COBE was dead or not.  In time, NASA came to view COBE as an important part of the agency's rehabilitation.  As a consequence, a rocket launch was approved, but the satellite had to be rebuilt, requiring a dramatic reduction in its allowable weight, a nearly impossible task.

The issues surrounding physicist George Smoot, co-winner of the Nobel Prize with Mather, are revealing about the difficulties that arise with this kind of project.  Mather and most of the management team were concerned about ensuring that proper credit would be given for the work done by members of the large team of scientists and technicians.  Too often, in the long history of the theorizing about, and the discovery of, the background cosmic microwave radiation, prior work had gone unacknowledged and credit was claimed and credit was disputed.  As a result, COBE had a publication protocol designed to avoid "the corrosive effects of a public fight over scientific credit."  (p. 254.)

Smoot was COBE's principal investigator for Differential Microwave Radiometer (DMR), the instrument measuring the differences in temperature across the background radiation which generated some of the most dramatic data from the project.  Mather describes how, before the agreed upon time and place for release of the COBE findings, Smoot violated the publication policy by going public with the DMR results, scooping the team and capturing the public's attention.  He became the central focus of newspaper and magazine articles about COBE, seemingly claiming credit for its work.  In the midst of the furor within the COBE team over this violation, it was discovered that Smoot had already secured a lucrative contract for a book about the findings.  Though he was ultimately forced to pen a quasi apology to the team, his act of ill faith appears to have gone unpunished and, even, in light of the Nobel Prize, possibly rewarded.

Smoot died earlier this year and his obituary in The New York Times reveals, in a genteel fashion, what appears to have motivated Mather to write his book (this helps explain his book's subtitle):

In his 1993 book, "Wrinkles in Time:  Witness to the Birth of the Universe," written with Keay Davidson, Dr. Smoot documented the process leading up to the discovery.  Some of his collaborators disagreed with his version of events and encouraged Dr. Mather to write his own account.  He did, publishing it three years later as "The Very First Light:  The True Inside Story of the Scientific Journey Back to the Dawn of the Universe," which differed from Dr. Smoot's version in some details.  (Katrina Miller, George F. Smoot, Who Showed How the Cosmos Began, Is Dead at 80, The New York Times, October 20, 2025.)

So, that's the book's first reward:  Mather wrote a very readable, informative, and often exciting account of the COBE project.

The second big reward?  As I noted earlier, a copy of Mather's book got into my hands too late to get it inscribed.  But, in a dramatic stroke of serendipity, here's what I saw when I first opened my used copy to its title page:

Call me Peter.

House Finches and the Prescient Charles Aiken

In a somewhat roundabout fashion, the three House Finches (Haemorhous mexicanus) shown below led me to Charles Edward Howard Aiken (1850-1936), an accomplished practitioner of 19th century ornithology and entrepreneur.  (Seen here are a male at lower right, female center, and a juvenile (?) upper left.  If, by some slim chance I've misidentified the bird, it doesn't really affect the course of this post.)  The spark that prompted my research voyage of discovery was in the species portion of the bird's scientific name:  mexicanus, suggesting what was the animal's original home range.  That I spotted these birds near a pond in Maryland suggested that there was a story to be uncovered here.

The guides I initially consulted to identify these birds offered a tantalizing bit of information in that regard.  Here is part of what David Allen Sibley says about the House Finch in The Sibley Field Guide to Birds of Eastern North America (2001):

Native to western North America; introduced to Long Island in the 1950s and from there colonized all of eastern United States and southern Canada.  (p. 412)

"Introduced to Long Island in the 1950s" - strikingly cryptic.  A later stop on my search was the entry for the House Finch in the Cornell Ornithology Lab's Birds of the World which elaborated a bit and made the bird's story more irresistible (A. Badyaev, et al., House Finch (Haemorhous mexicanus), version 1.0, 2020.  In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.):

From a few California individuals released from a pet store in New York City in 1939, and through natural expansion of its western range, in just a few decades this species came to occupy one of the widest ecological ranges of any extant bird. Originally a bird of hot deserts and dry open habitats of the southwest, it now occurs in nearly all types of landscapes and climates in North America, from edges of northern taiga to ocean coasts to metropolitan areas.

(Taiga is the boreal forest which, in North America, is the biome of most of inland Canada and some of the northern United States.)

Here is the map of the present range of the House Finch appearing in Birds of the World:

Yes, the two sources just cited differ in terms of the timing of the first appearance of the House Finch in the eastern U.S., and, frankly, neither is as entertaining as the possibly true explanation of how this bird came east.  In brief, that account has New York City pet store owners releasing the birds in 1940 ahead of a crackdown on their illegal trafficking in the animals, which had been sold as "Hollywood Finches" (the new name was a neat PR gimmick) and supplied to them by dealers on the west coast.  This version is described in some detail by Nicholas Lund in his article titled The House Finch (Audobon Magazine, The Sketch, July 15, 2016).  Even more detail, though not always consistent with Lund, is provided by John J. Elliott and Robert A. Arbib, Jr., in their piece titled Origin and Status of the House Finch in the Eastern United States (The Auk, volume 70, Issue 1, 1953, Digital Commons @ University of South Florida, September, 2024).

I searched for early 20th century guides to birds of the southwest U.S. to see what they might say about the House Finch and its range at the time.  Here is the range map that appeared in Field Book of Birds of the Southwestern United States (Luther E. Wyman and Elizabeth R. Burnell, 1925, p. 173.):

Wyman and Burnell noted that the House Finch was "a bird of familiar habits, cursed for the damage he does to fruit, but on the whole probably more beneficial than injurious."  (p. 172)

Comparing the two ranges maps shown above confirms that Badyaev et al., in Birds of the World, captured well the incredible spread of the House Finch across much of the U.S.

Yet, perhaps the most important find from my web search for early guides to southwestern birds was an initially puzzling hit, linking to what turned out to be a fascinating publication from Colorado College in 1937 titled Birds of the Southwest by Charles Edward Howard Aiken.  (Colorado College Publication, General Series No. 212, Studies Series No. 23, March, 1937.  The Aiken material was edited by naturalist Edward Royal Warren.)

This is not a guide to the birds of this region of the country, at least, not in any traditional sense.  Rather, much of it consists of the edited journals Aiken kept during a single trip in 1876 by mule-drawn wagon from Colorado Springs, Colorado, south into New Mexico, west across New Mexico to Arizona, and then south in Arizona.  His trek began on May 8, 1876, and ended with his return to Colorado Springs, probably in late November of that same year.  The objective of his journey:  collect birds and birds' eggs.  So, he shot and skinned birds as he went, and pilfered nests for their eggs.

This was ornithology as it was largely practiced in the 19th century.  Shoot and skin.  The rarer the bird, the more the incentive to collect its carcass.  It wasn't until the early and mid 20th century that the practice of ornithology moved from killing to observation.  Interesting and brief discussions of this change as it was sparked by some leading ornithologists can be found in two articles that appeared recently in Smithsonian Magazine:  The Hero who Convinced His Fellow Ornithologists of the Obvious:  Stop Shooting Rare Birds and Watch Them Instead (Tim Gallagher, Smithsonian Magazine, December, 2024) and How Bird Collecting Evolved Into Bird-Watching (Tim Birkhead, Smithsonian Magazine, August 8, 2022).

Though Aiken's journey undoubtedly fed the fledgling taxidermy business he began in Colorado Springs in 1874, and likely supported some trade in birds' eggs, it also reflected his deep interest in, and knowledge of, birds of the region.  Further, I suspect Aiken had a thirst for adventure, something that had manifested itself in the many birding trips he undertook beginning in1872, trips that built his avian knowledge.  That he was already recognized for this ornithological skills was evident by his work in the summer of 1874 as a naturalist with the Wheeler Survey (1872-1879), a survey organized by the U.S. Army Corps of Engineers to create topographical maps of the southwestern U.S.  In 1876, Aiken was certainly no birding neophyte.

In addition to his taxidermy business, Aiken was, at various times in his adult life, the owner of a "tannery and wool pulling factory," an employee of a firm selling pianos and sewing machines, the agent booking traveling shows, and a dog breeder.  His collection of some 5,000 bird skins and mounts were purchased and donated to the Colorado College Museum (subsequently donated to the University of Colorado (Boulder) Museum of Natural History).

(The biographical information about Aiken comes from the profile written by Edward Warren and included in Birds of the Southwest, and from the biographical description included in the finding aid to Aiken's collected papers held by the Colorado College.  The finding aid was written by Ginny Kiefer and published in September, 1984.  Her biographical material is based on Aiken's obituary that appeared in the Colorado Springs Gazette, January 16, 1936.)

Aiken is pictured below in 1874 in Pueblo, Colorado, sporting what may well be the equipment favored by 19th century birders.

(The date and identification of the location of this image are those provided in Wikimedia Commons.  The image is in the public domain.  This and other pictures of Aiken can also be found at a digital archive at the Colorado College website.)

His account of his 1876 trip is at times quite compelling for his interest in natural history was broad and, despite that fact that he had no apparent compunction about killing his quarry, he was a perceptive observer of birds.  As a record of what he saw and where, the journal is valuable (Edward Warren provided a catalogue at the end of this volume), though at times, the many names begin to blur.  This is balanced by his descriptions of the behavior of different bird species which are typically detailed and clear (certainly this was knowledge he needed if he wanted to get off a good shot).  Beyond the birds, he had an appreciative eye for the landscape through which he was traveling, noting changes in the vegetation, particularly the mix of trees, that marked differences in altitude and climate.  His prose never quite rises to the lyrical, but is frequently evocative.

The trip was arduous, often over roads that, I suspect, were roads in name only, and through areas with little water or vegetation.  During the summer months, the weather was particularly hot.  At one stage, he was seriously ill for several days.

While on the outward portion of his journey, Aiken entered Albuquerque, New Mexico, and there found a multitude of House Finches.  What he penned in his journal about this encounter is amazingly prescient, reflecting an understanding of the bird and its potential to live outside its native range of "hot deserts and dry open habitats of the southwest."  (As described by Badyaev, et al., in Birds of the World.)

At Albuquerque the Red-breasted Carpodacus (House Finch) was breeding abundantly, placing its nests on the beams of the plaza.  By the kindness of the hotel keeper I was allowed to secure a nest with three eggs from his building.  These birds are very tame, and as they are sweet singers and of bright plumage have quite a cheering effect about one's dooryard.  If they could be induced, as I think they could, to adopt for their homes the parks of our eastern cities they would be far preferable to the pugilistic foreigner (P. domesticus) [House Sparrow].  I think the former possess all the latter's good traits and none of their bad ones, and their pleasant song and bright plumage would make them much more attractive.  (p. 17)

(His disparagement of the House Sparrow is well taken because that bird is relentless in its efforts to control the nesting areas it prefers, driving out and killing members of other species that might attempt to occupy the same niches.  (See, for example, North American Bluebird Society, NABS Factsheet, House Sparrow Control, revised 2018.)  I'm with Aiken in thinking the House Finch is preferable to the little terrorist House Sparrow.)

When I compare the two range maps shown earlier, I wonder if any of the New York City pet store owners in 1940 who, one step ahead of the law, opened the cages and freed their Hollywood Finches, had any inkling of the consequences of what they were doing.  Aiken would have known.

Fossils and Glitter

I found a thought-provoking juxtaposition of fossils and that ubiquitous element of children's art - glitter - in a recent edition of the daily newsletter from Nature (Nature Briefing, October 14, 2025).  This issue highlighted the magnificent dinosaur trackways recently discovered in the United Kingdom.  Toward the end of the newsletter, the "Quote of the day" (a frequent feature) had the following statement:

A glitter container is never really empty.

A pretty sure way to grab this reader's attention.  The source of that quotation was an article about Edwin Jones, a forensic scientist well versed in the crime-solving attributes of glitter.  As we all know, glitter, once let loose, contaminates nearly everything and everybody.  Turns out, that can be quite helpful in linking individuals and objects to a crime scene.

Putting those two stories together reminded me of a passing comment I'd made long ago relating criminal forensic science to paleontology, specifically the subfield called ichnology, the study of trace fossils.  (See the post titled Ichnofossils and Old Home Movies, November 8, 2009.)  

It's useful to consider what we mean by forensic as an adjective and forensics as a noun.  The Latin root of forensic means of, or related to, the Roman Forum or with the courts of law.  (Oxford English Dictionary.  Sorry, it hides behind a paywall.)  The adjective was first used in English in 1647 and, in keeping with the Latin root, was applied to something associated with court proceedings or appropriate for use in court.  In the 1800s, the noun forensics was applied to the kind of rhetoric intended to argue or assert a point in a law court or in debate (particularly collegiate debate).  In the late 1800s, forensic science began to take on the meaning that, as a rabid consumer of TV shows featuring crime scene investigations, would expect of it (first use in print in 1893):

The provision of scientific evidence and testimony in legal proceedings; (in later use) spec. the application of scientific techniques and knowledge to the investigation of crime.  (OED.)

The article cited by Nature for the "Quote of the day" was written Jacqueline Detwiler-George.  It's a fascinating introduction to Jones and the role of glitter in forensic science.  (Inside the Glitter Lab, Popular Mechanics, September 26, 2025.  This article also resides behind a paywall.)   The article's hook is a fairly graphic account of the rapes committed by the Simi Valley rapist and the role Jones and glitter played in securing the death penalty for the perpetrator.  The investigator determined that glitter in the hair of a murdered victim was rather unique and he was able to trace it to the perpetrator's truck.

Detwiler-George identifies an important distinction in forensics between trace analysis and DNA analysis (forensic biology).  Of trace analysis, she writes:

In reality, it can include analyzing an absurd variety of materials.  It could be flame accelerant, explosives, cosmetics, carpet fibers, tree bark, hairs, shoe prints, clothing dirt glass fragments, tape, glue and, yes, glitter.

The latter, forensic biology, has come to dominate the field, relegating the former to the sidelines, partly because trace analysis requires expensive tools while DNA analysis has, I would surmise, such probative value.

It is trace analysis that really gave forensic science its original impetus.  Detwiler-George quotes the late Robert Blackledge, a forensic chemist with the Naval Criminal Intelligence Service (NCIS):  "Trace evidence analysis is the oldest kind of scientific crime-solving technique in existence."  One of the foundational beliefs for criminal forensics is the principle first enunciated by Frenchman Edmond Locard (1877-1966):  "Every contact leaves a trace."  I may be easily impressed, but I find that the Locard Principle profound and applicable well beyond crime scenes.

Having read about the glitter expert Jones before reading stories about the newly found dinosaur trackway, I found myself focusing on the steps being undertaken by the paleontologists to reconstruct the scene as it was in deep time.  Not a crime scene, I will admit, but, still, the impulse to reconstruct the events of so long ago, is, I think, akin to that undergirding criminal forensics.

I don't believe I am taking it too far to suggest that a variant of Locard's principle is at play in ichnology which works with fossilized evidence of ancient activity.  The fossil trackways described in the Nature newsletter are really spectacular examples of ichnofossils, which, in this case, date from some 166 million years ago.  (The link in the Nature article was to Rebecca Morelle, et al., How a Huge Dinosaur Trackway Was Uncovered in the UK, BBC News, October 14, 2025. See, also, Will Triggs, New Dinosaur Highway Dig Reveals Record-Breaking Footprints, EarthSky, October 15, 2025, and Oxford Researchers Return to the Jurassic Highway, University of Oxford, News, October 14, 2025.)

Clearly, the present day scene of the trackways (a quarry in Oxfordshire, United Kingdom) has been changed beyond recognition over the millennia, but the Locard principle - that contact leaves traces - still applies.  Not only were the tracks squished into the mud of the lagoon traversed by dinosaurs in the Late Cretaceous and then fossilized and preserved, but other traces of life and elements in the environment from deep time have also been retained at the scene.  Instructed by the glitter forensics article, I was particularly attentive to how the paleontologists uncovering, preserving, and analyzing the trackways took a broad view of the scene.  In this instance, they were not solving a crime, rather, they were reconstructing the events at a scene, and doing so without any eyewitnesses.  As a result, they have, as would good forensic scientists, to determine what messages the objects and traces found at the site could tell them about the events that had occurred here.

The trackways were found at the Dewars Farm Quarry and they are quite amazing, the longest stretching for 220 meters or 721 feet - the length of nearly 2 1/2 football fields.  They are the tracks of multiple individual Cetiosaurus dinosaurs, a massive herbivore, joined by a single trackway of a Megalosaurus, a large bipedal carnivore.  Certainly, paleontologists have experience with dinosaur tracks and can identify the likely animals that made them.  Still, unless the fossilized remains of the animal are found in conjunction with the fossilized traces, there's always some room for misidentification.

The paleontologists are attempting to reconstruct what the scene 166 million years ago was really like and, broadly, what happened here.  Duncan Murdock, one of the leaders of the project working on the trackways, has noted:

Unlike fossil bones, finds like these tell us about the behavior of extinct animals.  The size, shape and position of the footprints can tell us how these dinosaurs moved, their size and spreed.  And where trackways cross, we get a glimpse of the potential interactions between different species . . . .  (Triggs, EarthSky, emphasis added.)

The scientists determined the direction in which the animals were heading by careful study of the footprints.  At the front of each print is a protrusion which was left as the animal shifted its weight to the front of its foot when taking a step, squishing out some of the mud in which it was traveling.

Based on the number of footprints, Murdock observed that were "tens of individuals" crossing the muddy lagoon and, if, as is possible, they were present at the same time, what was captured by the trackways was herding behavior.  (Triggs, EarthSky.)

The single Megalosaurus track intersects the track of one of the Cetiosaurus dinosaurs leading to some speculation about the context and meaning of this interspecies encounter.

Reconstructing the scene has required looking for, and analyzing, evidence beyond the prints, and that evidence is emerging.  The paleontologists have found fossils from marine invertebrates, plants, and part of a crocodile jaw, and work is ongoing to analyze the content of the sediments under and in the prints.  (University of Oxford News.)  Murdock captures well the objective:

Along with other fossils like burrows, shells and plants we can bring to life the muddy lagoon environment that dinosaurs walked through. (Triggs, EarthSky.)

In the end, I wonder if ichnology, in general, might be termed a form of forensic paleontology?  At a minimum, it seems to be a field in which some of the methods of forensic science are applied to fossils in an effort to describe and, perhaps, explain the behavior behind fossilized traces of activity.  In other words, to reconstruct a scene and the events that took place there.

For a fascinating look at how some paleontologists have applied the analysis methods used in forensic entomology, I would recommend the article by paleontologist Kenneth S. Bader and colleagues describing their analysis of a cache of dinosaur bones from the Jurassic found in Montana.  (Bader, et al., Application of Forensic Science Techniques to Trace Fossils on Dinosaur Bones from a Quarry in the Upper Jurassic Morrison Formation, Northeastern Wyoming, Palaios, Volume 24, 2009, p. 140.)  We're all familiar with the forensic scientist on TV extracting a beetle larva from a corpse and announcing how long the body had been exposed to the elements.  That's forensic entomology at work, bringing to bear on a crime scene the understanding of when and how insects and other arthropods will work on the flesh and bones of dead animals, what evidence they leave of their presence, and what that evidence says about the environment in which the body lay.

Based on the evidence gathered by using these forensic techniques, the authors describe in wonderful detail a scene from millions of years ago:

These events were initiated during the dry season, and were likely part of a prolonged drought, based on our interpretation of the levels of articulation for each of the sauropod skeletons, bone modification features found on those skeletons, and previous interpretations of the Late Jurassic paleoclimate recorded by the Morrison Formation [citations omitted].  The evidence suggests that sauropods were drawn to this area for its water availability over an extended period of time.  Fossils of turtles, fish, crocodiles, snails, and bivalves support the notion of a relatively permanent body of water.  A prolonged drought is thought to have occurred based on the different conditions of the sauropod skeletons, which suggest that the area was not resubmerged with differential burial of the skeletons.  Only after all the sauropod skeletons accumulated, the soft tissue decomposed, and the bones were bored, did the drought end and the accumulation of skeletons was buried.  A short duration of pedogenesis [the formation of soil] took place before additional sediments covered the area of the skeletons likely through a period of regular succession of wet-dry seasonal climates.  (p. 156)

All that's missing is an explanation of the glitter found at the scene.