Fossil Friday


Specimens of siderite (an iron carbonate mineral) are among the most common rocks brought in off the Mississippi River for identification.  They are unusually heavy for their size and range in color from black to red-orange and typically exhibit very shiny polish on the surface of the stone. They are often mistaken for a variety of things such as meteorites, fossil bones and teeth, and even dinosaur skin impressions due to their wide range of unusual shapes, sizes, and textures.  Siderite forms naturally from the geochemistry of the groundwater of the Mississippi River’s alluvium.  This mineral can indeed replace (mineralize) organic materials such as fossil bone, wood, and apparently even mollusk shell by occupying tiny pore spaces of these organic materials.  One particularly interesting specimen was brought into the Museum of the Mississippi Delta by Laura Sanford during a fossil road show in late October in Greenwood.  It was identified by at the special program by Office of Geology staff as a rare occurrence of a Pleistocene age, siderite-replaced freshwater mussel shell from the alluvium of the Mississippi River.  This unusual ice-age mollusk fossil was collected on the Louisiana side of the Mississippi River in East Carroll Parish. Geology staff identified it as Potamilus purpuratus, also commonly known as Bluefer or Purple-shell mussel, aptly named for its distinctive beautiful purple color mother-of-pearl of this species, which still inhabits many rivers in Mississippi and Louisiana today.  The excellent presentation of this fossil freshwater mussel exhibits both valves of the shell still articulated (attached) in typical mussel death position (shell open).


This week, just minutes after MDEQ’s Surface Geology staff Jonathan Leard successfully defended his masters thesis at Mississippi State University on the first detailed geologic map of the Starkville area, he was found studying an important and newly exposed geologic outcrop just off of campus. Here he explains to MSU freshman anthropology student, Abigail Starnes the important geologic contact that is represented in the fresh excavation.  The lighter-colored rock unit below, is a limestone called the Prairie Bluff Formation.  It from the Late Cretaceous period and is chock full of marine sea shell fossils that were some of the last things alive in the ocean just before the meteorite struck the earth that killed off the dinosaurs some 66 million years ago.  The darker-colored deposits above the limestone are significantly  younger and are from the late Pleistocene.  It  contains the fossilized remains of extinct ice-age land animals that the first people in North America and the first Native Americans to arrive here in Mississippi would have encountered.  The contact between these two geologic units is called an unconformity because it represent missing time between the two formations.  In this case, a hiatus of tens of millions of years, which can only demonstrated by studying the abundance of different fossils contained between the two geologic units at this outcrop.


The current near historic low of the Mississippi River has it’s dry banks exposing miles of seemingly endless sandbars that are now, once again, sharing its ice-age secrets from the river’s depths.  Pleistocene fossils from extinct beasts such as American lion, giant bison, mastodon, saber toothed cats, horses, giant ground sloths, tapir, gomphothere, pampather, and dire wolves that once hunted and grazed along the forests and wetlands of the Mississippi River floodplain have now been exposed along the now barren river bottoms.  Surface Geology staff joined the Mississippi Museum of Natural Science and USFWS scientists this week along the banks of Mississippi River in Warren County to help understand and to better document these important paleontological resources during this unique environmental opportunity.

During this field trip an important discovery of a fossil of an ancient bear-sized rodent, a giant beaver called Castoroides ohioensis, was made by biologist Paul Hartfield during the trip.  Paleoindian cultures, the first human inhabitants of Mississippi, likely shared their environment with this and other strange Mississippi ice-age beast.

Additionally, a larger ice-age Mississippi River bottomland ecosystem was documented during the study which included fossils of giant catfish, gar, turtles, alligators, giant bison, deer, elk, mastodon, mammoth, and horse.  These fossil specimens will be accessioned into the Mississippi Museum of Natural Science paleontological collections for public display and for scientific study.

As the glacial climate ended and the environment rapidly changed along the Mississippi River at the close of the Pleistocene,  the ice-age megafauna gradually became extinct. People persisted along the great river and they, along with the ecosystem began to adapt to a world that we are more familiar with today.


The first people, to inhabit the Mississippi’s Northwest Delta region towards the end of the last ice age lived in quite an unfamiliar world than that of today.  It was once thought that this area,  known today as the Yazoo Basin, was an environment called as “braided stream”, a formidably unstable landscape that would have been largely uninhabitable by these first people known as Paleoindian cultures.

This idea was only just recently dispelled by research that identified numerous Paleoindian archaeological sites and used it to date landforms within the Yazoo Basin.  This important research was published on by a team of scientists from the Office of Geology and the L.B. Jones Trust.  The L.B. Jones Trust is an important archaeological and paleontological collection housed at the Museum of the Mississippi Delta for the preservation of Mississippi Delta history and scientific research.  View the Office of Geology publication here.

As glacial ice was making its final retreat into the arctic, these ice age Paleoindian hunters here in the lower Mississippi River valley encountered a bounty of wildlife along the meanders and back swamps of the great river.  Familiar to these first people of the Delta were animals such as American lion, giant bison, mastodon, saber toothed cats, horses, giant ground sloths, and dire wolves that hunted and grazed along the forest and wetlands of the Mississippi River floodplain.  As the climate rapidly changed at the close of the Pleistocene and the megafauna gradually became extinct, people in the Delta during the Early Archaic cultural period adapted to their surroundings.

Remains such as fossil bones and teeth of these extinct ice-age beasts that once inhabited the Delta can still be found along the gravel bars of the Mississippi River today.  Featured in this week’s fossil Friday is the portion of a fossil jaw from bear-sized ground sloth, Paramylodon harlani, commonly known as Harlan’s ground sloth.  It was collected in Washington County, Mississippi by L.B. Jones Trust chairman and researcher, Anna Reginelli and identified this week by Office of Geology Staff.


As geology is the basis for the environment, geology staff is often involved in multidisciplinary research with other agencies and institutions. Yesterday, Geology staff assisted the Mississippi Museum of Natural Science conservation biology team in a freshwater mollusk survey being conducted on the Pearl River in Marion County.  During Thursday’s survey, State Ichthyologist, Robbie Ellwanger discovered a bone from a very large turtle amongst the gravel in the river.  The bone was identified by geology staff in the field as an ice-age fossil turtle and the specimen was collected for study. Vertebrate fossils from this part of Mississippi are very rare and are essential to our understanding of the geologic history of the area.  Once the team returned to the museum, Paleontologist George Phillips further identified the fossil bone as a piece of a large alligator snapping turtle shell. This find is a first for the area, making it an important contribution to the fossil record.

The alligator snapping turtle (Macrochelys temminckii) is the largest species of freshwater turtle in North America.  Individuals of this icon reptile can live over 100 years and grow to be more than two hundred pounds.  The family that includes these turtles goes back to the days of the dinosaurs during the Cretaceous period.  Very little is known about alligator snapping turtles in the fossil record and most material available for study comes from ice age river and swamp sediments deposited during the Pleistocene. They are currently listed as a vulnerable species in need of conservation efforts.  This important fossil specimen will be accessioned into the Mississippi Museum of Natural Sciences paleontological collections. There, it will help scientists to better understand the Pearl River’s ancient geologic past and will also help in studies of this living fossil in North America.

Mississippi’s wealth of well-preserved fossils  have been studied by researchers from all over the world for more that two centuries.  That tradition continues through to today as MDEQ,s geologist performs the work of Mississippi’s Geological Survey in studying the state’s natural resources and its natural history. The fossils contained in the various geologic deposits around the state hold important clues to past life, past climates, and past ecosystems. What our scientists learn has implications for not just here in Mississippi but also around the world.  Fossils are important tools for geologists to help map geologic formations and to correlate rock units far beyond the boarders of the state.  The scientific value of invertebrate fossils such as ancient marine mollusk shells are very important in this respect.  Our State Geologist, Dr. David T. Dockery is an invertebrate paleontologist who’s research focuses specifically on studying, naming, and describing these important resources.  Following recent publications on hid studies of fossil mollusks from the Late Cretaceous deposits of northeastern Mississippi, 27 holotypes of new fossil gastropod species were sent to the Smithsonian this month to be archived in the U. S. Natural History Museum’s collections.


This Late Archaic cultural period Native American artifact, utilized as hammer-stone, was collected off a prehistoric archaeological site by an oxbow lake near Satartia in Yazoo County, Mississippi.  It was utilized sometime between 2,000 BC and 800 BC from a large Stromatoporoid chert gravel fossil.

Stromatoporoids were reef-forming sponges from the Devonian period (some 400 million year old). They are found among the gravels of ancestral Mississippi River Pre-loess Terrace Deposits, beneath the loess along the western bluff line overlooking the Mississippi River Delta region, from Memphis to south of Natchez. Their natural presence and abundance in these Pre-loess Terrace gravels helps to mark a geologic shift in drainages of the exposed bedrock sources in the upper reaches of the Ohio River Valley region during glaciation of the mid-Pleistocene some 700,000 years ago.

They are curiously absent from our older (pre-glacial) Pliocene age High Terrace gravels further east in south-central Mississippi. The occurrence of these chert fossils in archaeological context at sites has been observed broadly across the MS Delta Region and also, as far east of the bluff-line as Smith County in Mississippi. This helps demonstrate a relatively long distance prehistoric cultural trade of these high-quality, larger chert clast-size gravel resources that emanated from the Mississippi loess bluffs region, east into areas with limited and poorer quality available resources.

Special thanks to Jim House of the Mississippi Archaeological Association, Madison Chapter for allowing MDEQ, Surface Geology staff to identify and photograph this remarkable fossil artifact specimen.

Linked below is the MDEQ FossilFriday post from September 6, 2019 featuring another interesting stromatoporoid fossil culturally utilized as an ancient artifact.  It is polished mano artifact collected from an archaeological site along the Leaf River in Smith County, Mississippi. This was found roughly 100 miles east from its original natural source in the Loess Bluffs. The use-wear exhibited on the mirror-like, highly-polished surface of the artifact exposed incredibly detailed features of the fossil’s mamelon and astrorhiza structures.

Click here to learn more about the Smith County Stromatoporoid Artifact Specimen:


The revelations garnered from our recent geological mapping work on the timing and evolution of the lower Mississippi River Valley, has lead to the development of a new framework to better understand the environmental effects of the cyclical glaciation on the lower Mississippi River valley and it’s geology.   Our work has identified Pleistocene deposits containing a host of well-preserved flora, faunal, and even early cultural remains that have yet to be fully studied and relayed in their proper context.

Core samples were taken today during a drilling projects to study an uninterrupted stratigraphic section of an ancestral Mississippi River Pre-loess Terrace Deposits in Jefferson County, MS. This terrace is blanketed by more than 70 feet of loess cover, masking a perfectly-preserved paleosol and surfacial clay stratum from the alluvium of the ancestral Mississippi River during the last interglacial stage of the Pleistocene. This is just  before the river abandoned this level and began cutting its present valley during the last glacial advance.

Radiometric dating of these core samples is planned and will necessarily benefit our stratigraphic understanding along. Palynological research for paleoenvironmental context will be done, as well.

Outcrops of this terrace have been described along the river in the early literature as the “Natchez Formation” but the extent and context of it has only been recently understood.  We have mapped the extent of this level of Pre-loess Terrace from southern Claiborne to Adams County.

The expression of this loess-draped terrace surface is heavily dissected today by erosion. But during the last glacial episode, it hosted a lush broad and level prairie environment overlooking the Mississippi River and boarded to the east by the older aggressive uplands.

Thanks to the work of George Roberts, a host of well-preserved late Pleistocene Megafauna remains have been recovered from the drainages that dissect this feature along with artifact evidence of early habitation from Paleoindian and early archaic cultures. Undoubtedly this is just scratching the surface of what is preserved here.

Within the last few thousand years this feature has undergone erosion, but still was was considered ideal for habitation into the later cultural periods.  Iconic archaeological sites such as Feltus Mounds, Anna Mounds, Windsor Mounds and Windsor Ruins are just a few of studied sites adorning the expression of this terrace surface. — with Paul Parrish and Jonathan Leard.


Geology is the basis for the environment and fossils are an important tool for our scientists that study Mississippi’s geology.  These ancient clues provide us the necessary details to understand the age, depositional environments, and layered sequences that make up the geology of our state.  Many people think of Mississippi’s fossils as the large ancient bones and numerous sea shells which can been found throughout the state.  But many of the most important fossils we study can’t be seen with the naked eye.  Billions of tiny skeletons of animals called foraminifera make up much of our state’s limestones and other marine deposits while tiny grains of fossil pollen and spores from ancient plants can be quite abundant and exceptionally well-preserved in many of our terrestrial deposits.  Studying these sequences of alternating terrestrial and marine environments helps us to understand past climates and how it has changed over geologic time.  While much work has been done on our marine fossils, comparatively little is known about these fossils from our terrestrial environments.  Over the past decade, MDEQ’s Surface Geology and Mapping program has been collaborating with a number of universities and institutions to better understand these terrestrial environments and the fossil plants and animals they contain.  This team includes researchers from Delta State University, The Smithsonian Intuition, University of South Alabama, Mississippi Museum of Natural Science, University of Southeastern Mississippi, and many others.  Recent work has been focused on the plant fossil of the Lower Oligocene age Forest Hill Formation while sampling several outcrops during geologic mapping across the central part of the state.  The contact between terrestrial Forest Hill Formation and underlying marine deposits of the Late Eocene age Yazoo Clay mark an important boundary in earth’s climate history, some 34 million years ago.  The earth had been in a tropical greenhouse environment for tens of millions of years, going back to the days of the dinosaurs, and then suddenly began to cool at the close of the Eocene epoch.  This climate shift is recorded in the fossils in both the Eocene and Oligocene age rocks of Mississippi and studying it is important to furthering our understanding of this time period.  Preliminary research findings of the palynology (tiny fossil plant pollen and spores) from our sampling efforts of Forest Hill Formation were presented in a poster by our study’s lead author from Delta State University, Dr. Nina Riding last month at the Botanical Society of America’s conference in Anchorage Alaska.  Surface Geology staff is proud to be a part of this research team.  These collaboration efforts in various aspects paleontology continue to expand our understanding of Mississippi geologic past.


To learn more about Mississippi’s Geologic past here.

To learn more about Mississippi’s Cretaceous Geology here.


Do you have a rock or fossil that you want more information on? Click here to Ask a Geologist.


Humans entered the paleontological record in Mississippi at some point during the last ice age.  The Native Americans that first arrived in Mississippi encountered an environment that would seem quite strange to us today.  The plants of the forests and prairies would be more familiar to modern northern climates than to those of Mississippi today. The landscape hosted animals that are now long extinct such as mastodon, mammoth, giant beavers, ground sloths, horses, and giant bison.  These animals were hunted by predators such as saber-toothed cats, dire wolves, and these first peoples.  Lower sea levels exposed land far into the Gulf of Mexico miles beyond the barrier islands of today as evidenced by the Office of Geology Mapping in Jackson County, MS as well as an ice-age forest exposed by Hurricane Ivan in 2004, 60 feet beneath the Gulf of Mexico, south of Gulf Shores, AL.   

 

Geology is the basis for the environment and an integral part of archaeology.  Geologic mapping is essential to understanding the age of landscapes and their paleoenvironments, as well as characterizing depositional environments and the geochemistries conducive to the preservation of these important archaeological resources. The tools these first people left behind in Mississippi are the only evidence we have to study and learn about these first peoples’ relationship with their environment.  

 

These ice-age cultures are known collectively as Paleoindian.  They were thought to be highly specialized and nomadic hunters as evidenced by their exquisitely made tools and the scarce number of longer-term occupation sites that they left behind.  The discoveries of most known early Paleoindian artifacts are by landowners, collectors, and hobbyists, and not made by researchers in the field.  This makes the general public, those who have found and collected these artifacts, the most important resource for information scientists have to study this early time period in Mississippi’s prehistory. 

 

 On June 14, 2022, a very important discovery was made of an early Paleoindian point in Perry County, Mississippi by Matthew Sullivan, an artifact enthusiast and Circuit Court Judge for the 13th District of Mississippi while he was rock and artifact collecting with his friends. Realizing the significance of his find, Judge Sullivan brought it to the attention of the Surface Geology staff for examination.  Retired archaeologist, Samuel Brookes consulted on the find during Judge Sullivan’s visit.  The artifact was identified as a Clovis point making it approximately 13,000 years old.  Geology staff identified the stone as a rare form of pure chalcedony not naturally occurring here in Mississippi.  

 

Geology staff collected additional laboratory data on the point and consulted with geological surveys in nearby states to conclude the bedrock origins of the stone.  The Judge Sullivan Clovis was manufactured from a type of pure chalcedony from agate replacement of fossilized coral.  It is an extremely high-quality, translucent stone found only in Miocene and Pliocene age rock outcrops in Florida.

Geological resources naturally available to prehistoric cultures for stone tool manufacturing in the part of southeast Mississippi that The Judge Sullivan Clovis was found are scarce according to recent research published by Office of Geology staff.  The discovery of The Judge Sullivan Clovis is important to science because it demonstrates the movement of people and material from east to west through south Mississippi during this ancient time in Mississippi’s ice age history.


Mississippi has a rich geologic past with a fossil record that includes a history in the Mesozoic era, also better known as the days of the Dinosaurs.  Outcrops from the Late Cretaceous period underly the rich soils of the Black Prairie and uplands of the Pontotoc Ridge physiographic regions of northeast Mississippi.  Much of these deposits were formed in warm tropical shallow seas teaming with life and now rich with their fossil remains.  While the dinosaurs walked on land, giant marine reptiles and sharks ruled these ancient seas.  Fossil bones and teeth of these animals are commonly found along an abundance of ancient sea shells from mollusks in most outcrops of Cretaceous age in Mississippi.  The currents, waves, and storms along with scavengers tend to widely scatter these  remains. Therefore, actual fossil skeletons of these animals are important and rare finds.  Last month, Surface Geology staff partnered with vertebrate paleontology staff at the Mississippi Museum of Natural Science, to excavate an intact skeleton of a sea dragon, called a Mosasaur.  The recent discovery was made by museum staff conducting fieldwork near Westpoint, Mississippi. This species of Mosasaur, known as Clidastes propython, is approximately 80 million years old.  Though typically only isolated bones and teeth are ever found, this is the most common mosasaur found between the geologic units of the Tombigbee Sand and the Arcola Limestone at the top of the Mooreville Chalk/Formation. This find was in the middle part of the Mooreville Formation above an important geological mapping marker that can be traced a long distance, a fossil bed made up entirely of the extinct oyster called Ostrea falcata.  The team managed to excavate portions of the skull (with teeth still intact) along with a number of vertebrae and some rib bones.  This important specimen will be carefully reconstructed and curated for future study. #fossilfriday


During the last ice age, the prairie regions of northeast Mississippi were an environment that was a paradise for a host now extinct Pleistocene mammals and other ice age megafauna.  Gently rolling grasslands were once broken by streams with broad alluvial plains boarded by bottomland forests.  Saber-toothed cats, American lions, giant ground sloths, mammoths, mastodon, giant bison, giant armadillo, giant elk, giant tortoises, and even herds of horses once roamed this rich dark soils region.  Paleoindian cultures, such as Clovis were among the first human inhabitants to Mississippi, some 14,000+ years ago, and were certainly witness to these great animals of long ago and exploited the bounty of this Mississippi ice-age ecosystem.  Fossil bones of many of these extinct animals are commonly found in stream alluvium of the Black Prairie region of northeast Mississippi.  Pictured is a large unidentified ice-age fossil mammal bone exposed along an outcrop of Pleistocene age stream alluvium that was encountered by MDEQ, Surface Geology staff while conducting field work this week in Clay County with the Mississippi Museum of Natural Science while studying the underlying Cretaceous geology bedrock.  The natural weathering of these chalky limestones over the course of tens of thousands of years form the dark rich soils for which is the basis for this prairie environment.


The last days of the dinosaurs ended some 66 million years ago when a giant meteorite impacted the Gulf of Mexico and created a world-wide extinction event which instantaneously changing Earth’s environment, climate, and devastated ecosystems.  As the work of the State’s Survey, research is being conducted by MDEQ’s Office of Geology staff this week in the Starkville area to map and delineate geology representing this time.  This will be used to better understand this important time in Earth’s history, both before and after this event, which is best recorded in our geologic record in northeast Mississippi.  Featured here are Late Cretaceous marine fossils from the Prairie Buff Formation that are being studied by our scientists from outcrops in Starkville area. Fossils from this time not only include the infamous dinosaurs, but also important invertebrate fossils, part of a once thriving diverse tropical marine ecosystem.  This is represented in the Prairie Buff Formation by an abundance of giant extinct fossil oysters, clams, and snails that once inhabited the sea floor of the during the Late Cretaceous, just moments before the extinction event. #fossilfriday


Gravel fossils are many Mississippi folk’s (especially children) first exposure to paleontology. These ancient tiny fossil treasures can commonly be found along gravel roads and driveways, along creeks and streams, even on school playgrounds throughout much of Mississippi.  Seven year old Fen Anderson, a budding geologist from Yazoo County, recently shared his discoveries with MDEQ, Office of Geology scientists. These tiny ancient sea creature fossils are of solitary rugose corals and crinoid stems from Paleozoic era, making them older than the days of the dinosaurs. His awesome fossil collection pictured here came from just one day’s worth of searching through playground gravel at Manchester Daycare. #fossilfriday

For more on collecting rocks and fossils from Mississippi gravel, click here. 

 


Ichnology is a discipline of Paleontology that is the scientific study of tracks and trace fossils.  Knowing what kinds of animals occupy certain depositional environments, the traces and tracks they leave behind, and an understanding of geochemistry help us to translate ancient geologic outcrops.  This beautiful example was collected in Lauderdale County by Leslie Potter and sent to Office of Geology staff this week for identification through our “Ask a Geologist” online public outreach program. These excellently-preserved fossil decapod burrows are part of the Lower Eocene age Tallahatta Formation.  This ichnofossils is named Thalassinoides and were made by numerous marine burrowing shrimp that once occupied a tropical sandy shallow sea floor that once occupied the east-central Mississippi area some 50 million years ago. They are preserved as stone casts from being naturally cemented with silica minerals that have now become harder than the surrounding sandstone so that they weather in relief.  Because the chemistry of the sediments didn’t preserve any other fossils of marine life that once certainly occupied the area, these ichnofossils prove important to helping us understand the ancient depositional environment of the sandstones of the Tallahatta Formation.  Every so often some rare fossil sea shell impressions have been found there but are extremely rare, whereas these Thalassinoides burrows are quite abundant.  This one in particular is a pretty special find.  The gassy-fill substance in the burrow is called Tallahatta Agate.  It is a natural mineral formation of nearly pure chalcedony and opaline silica.  Thank you again Leslie Potter for sharing your discovery with our geology research staff and allowing us to share it with others.

Click here to learn more about Lauderdale County geology


Ancient marine fossils, much older than the days of the dinosaurs can be found in chert gravels right here in Mississippi. This crinoidal chert (a type of rock that was once the sea floor dominated with the skeletal remains of fossil crinoids) from Jefferson County was photographed this week by Office of Geology staff.  Complete fossils of crinoids are rarely preserved intact, though there individual segments and partial stems and calyx are some of the most common chert gravel fossil found in Mississippi. Crinoids are echinoderms, relatives of starfish and sand dollars and are still alive today in the worlds oceans.  Paleozoic era chert gravel fossils from Mississippi can be found naturally though much of the state. They were once eroded from ancient limestone bedrock sources north of here, up in the mid-continent, and were brought down and deposited by by ancient rivers flowing to the Gulf of Mexico. Collecting gravel fossils are often the first exposure folks have to our rich paleontology resources in Mississippi. Crinoids are one of the many treasures to be found in our Mississippi chert gravels. Chert gravels is an important economic resource commonly used in many civil applications throughout Mississippi. So, gravel fossils can be found almost anywhere from playground, aggregate, to gravel roads and driveways, even in cement gravels along downtown sidewalks.

 

Click here for more information on Mississippi gravel fossils.


Calcite septarian nodules (commonly called dragon stones) are natural concretions of calcium carbonate that exhibit secondary mineral growth of yellow “dog-tooth” calcite along an intricate network of desiccation-like  cracks. They make excellently beautiful mineral specimens, especially when they are carved, cut, and polished or as interesting curiosities if left natural. They typically form in impure, sandy, and fossil shell-rich limestones (called marls) from the geochemistry and movement of shallow groundwater. Groundwater moving through the marl formation derives carbonate minerals from dissolving and leaching from fossil sea-shells in the rock and concentrates it into a nodule. As the nodule solidifies to a hard rock it begins to shrink and a network of cracks form throughout the nodule. The voids created by the desiccation-like cracks then begin growing “dog-tooth” yellow calcite mineral precipitated from the carbonate-rich groundwater water.  These nodules are much harder and more erosionally-resistant than the surrounding geologic formation they formed in. Therefore, they tend to weather in relief from the outcrop or completely weather out and can concentrate as unusually large bolder-gravels along stream beds that wind their way through the formation.  Only a few geologic formations in Mississippi exhibit this phenomenon. Most notably is the early Eocene age Bashi Formation of east-central Mississippi in the vicinity of Meridian. Another example (photo below) of exceptional quality was recently documented by MDEQ, Office of Geology staff from the Late Eocene in age Moody’s Branch Formation while describing geologic outcrops in the field with in Yazoo County, Mississippi.

Click here for more on Mississippi’s Geologic past.


Ichnology, a discipline of Paleontology, is the scientific study of tracks and trace fossils.  Knowing what kinds of animals occupy certain depositional environments, the traces and tracks they leave behind, and an understanding of geochemistry help us to translate ancient geologic outcrops. These excellently-preserved fossil decapod burrows where photographed in the field last week by MDEQ, Office of Geology staff. The fossil burrows were discovered eroding from an Eocene (Claiborne age) outcrop of the Creola Member of the upper Cockfield Formation exposed in the creek floor. They are preserved as stone casts from being naturally cemented with siderite, a distinctive iron carbonate mineral. Siderite commonly forms in shallow marine, brackish water, near-shore environments. With these clues found in the outcrop in the floor of the creek along with numerous seashell fossils it contains, it’s not hard to imagine a place very much like the Mississippi Sound today…shallow muddy water filled with burrowing crab and shrimp, as well as snails, oysters, and clams while drum fish, sea trout and flounder tail along the grassy shallows…but this is almost 40 million years ago, in a world filled with much more stranger beasts…and in Yazoo County, Mississippi. #fossilfriday