After the Apocalypse: My House at 20, 100, and 10,000 Year Intervals

September 23, 2016

Alan Weisman’s book, The World Without Us, in part inspired my blog.  In his book he imagines a world where humans suddenly become extinct, and he speculates about the resulting ecological changes and how anthropogenic structures would decay.  I am particularly interested in landscapes devoid of human influence.  I chose to devote my blog to the paleoecology of southeastern North America as it was before people lived here, rather than after people become extinct.  But for this blog entry, I am going to speculate about what changes would occur to my lot and my immediate neighborhood, if a plague suddenly wiped out 100% of worldwide humanity.

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Without anyone around to maintain it, my house would become covered in grape vines, Virginia creeper, and pine straw in 3 years.  After 100 years the only thing left standing would be the chimney.  Sand, held down by pioneer plants, would cover the road completely.

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During the growing season, I have to  constantly cut back the Virginia creeper that otherwise would completely cover my house.

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My peach trees would probably die in less than 20 years, but my blueberry bushes, persimmon and mulberry trees, and chives would likely still be alive after 20 years.

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My patch of sunchokes would last decades…until trees shaded them too much.

My House 20 Years After the Extinction of Homo sapiens

I rake the pine straw off my roof twice a year and cut back Virginia creeper and grape vines twice a month during the growing season.  Without me all 3 completely covered my house in 3 years.  This hastened wood rot.  A sagging area of my roof caved in and several generations of squirrels have lived in the attic.  The house is still standing, though the roof leaks in numerous places and the inside smells like mildew.  An oak tree in the front yard is now quite large and some of its branches cover my daughter’s Toyota Corolla.  The tires on both Toyotas are flat, and the metal bodies are rusting.  A hailstorm cracked windows, and some are shattered.  Mosquitoes breed in puddles on the floorboard of 1 of them.

The peach trees in my scrub-covered backyard have died, but the mulberry, a native tree, is thriving and forms a closed canopy on the side of the yard with a black cherry and oak.  Both native fruit trees provide plenty of summer food for songbirds.  Much of the backyard is near impassable thicket and home to a happy family of rabbits.  The lot across the street from mine is also a thicket of pine and oak saplings and persimmon, most of it covered in vines.  Before people became extinct, a street sweeper kept sand from covering the road in front of my house.  But now most of the road is covered in sand, leaves, pine straw, and other organic debris; and pioneering grasses and flowers are taking root in many places.  The road is the only passable track in the vicinity and serves as an animal trail.  Scat of all kinds is visible.

Human hunters and automobiles caused a 30% annual mortality rate in the deer population.  But after humans became extinct the deer population skyrocketed, and it is still high 20 years later.  Herds of 200 occasionally form, and they browse down much  of the vegetation but here in the south with a long growing season, they never starve.  Instead, predator populations increased and partially keep the deer population in check.  Both coyotes and bobcats take a toll, especially on spring fawns.  Wild hogs have expanded out of nearby Phinizy Swamp and are regular travelers along the road.  They eat pine sapling roots and acorns but don’t seem to be having a big impact on the dense young forests popping up everywhere.  Rabbits like the yards that have become covered in scrub habitat.  Feral cats hunt them.  They are still abundant but suffer shorter lifespans without people feeding them.  Packs of feral dogs are uncommon because coyotes outcompete them.  Cougars and bears are increasing elsewhere but have not yet colonized the vicinity.

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Without humans cats would be just as abundant as they are now, but they would have shorter lifespans.

My Lot 100 Years After the Extinction of Homo sapiens

The chimney is the only structure still standing from my old house.  Most of the houses on this street look like collapsed ruins.  Some power line poles have rotted and tipped over, and during several ice storms trees smashed through power lines.  About half the poles still stand but the wire is all on the ground covered in dense vegetation.  The ground around my former home is littered with bricks, most covered with dirt, grass, leaves, and pine straw.  A sapling is growing through a crack in the cement slab that my house formerly rested upon.  The rusty washing machine and dryer are covered in brambles.  There is a squirrel’s nest on top of the refrigerator.  A rotting pine log and all sorts of organic crud camouflage what used to be a queen-sized bed. The fabric rotted away, but the springs and metal parts can still be seen. An oak is growing through 1 of the rusted hulks that used to be a car.  My backyard is a thick forest.  However, the lot across the street is more of an open woodland.  Perhaps a fire burned through that side of the road.  The road is not recognizable–scrub vegetation broke through cracks in the pavement which is now only visible in a few eroded places.  However, an animal trail still winds around in the general direction of where the road used to be.

Deer and wild hog are still abundant and are preyed upon by coyotes and bobcats here, but a cougar includes my lot as part of his territory.  Bears occasionally pass through too, looking for turkey eggs, for there is a big flock roosting in the vast local woods.

My Lot 10,000 Years After the Extinction of Homo sapiens

There is no trace of my house, at least on the surface.  Bricks, metal, and plastic are buried under several feet of sediment.  The surrounding landscape is an open woodland consisting of loblolly pine and sand laurel oak–the species that have long co-dominated this belt of fall line sand hills.  The trunks on many of the oaks are 6 feet thick, but the poor soil keeps them from growing very tall.  Fire and megafauna foraging maintain a grassy understory between the widely spaced trees.  The climate is beginning to gradually sink into an Ice Age, but the change is imperceptible to the great herds of horses, long-horned cattle, bison, wild boar, and deer that live in the vicinity.  Jaguars long ago joined the cougars and wolves in hunting the hooved animals.  The wolves descend from coyote x dog hybrids.  They evolved to a larger size that helps them bring down larger prey.  Bears are abundant, but feral cats, along with other small predators such as raccoon, fox, and opossum are less common than they were in anthropogenic environments because the larger predators keep their populations in check.  It’s almost like the Pleistocene again.

 

Possible New Megafauna Kill Site Found in Mexico

September 18, 2016

Whenever news organization report new paleontological discoveries, I can always count on the journalist to sensationalize the find, and they often make assumptions that are factually incorrect.  Here is an example.  A mostly complete Columbian mammoth (Mammuthus colombi) was unearthed in Tultepec, Mexico in December 2015 when workers digging a trench for a new sewer line found the bones 6 feet below the surface of the ground.  Luis Cordoba Barradas, a Mexican archaeologist, took over the excavation.

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Location of Tultepec, Mexico where the remains of 1 mammoth were found 6 feet underground.  It may have been butchered by humans.

Mexican archaeologist Luis Cordoba works on parts of a skeleton of a mammoth discovered in December 2015 in Tultepec, Mexico 

Mammoth skull with intact tusks in the process of being excavated in Tultepec.

Over a dozen news services reported the discovery, but important information is missing from all the reports.  This particular mammoth lived some time between 14,000 BP-12,000 BP and was 20-25 years old at the time of its death.  According to all the reports, the position of the bones suggests possible human butchery.  But this is a sensationalist overreach because many of these reports left out the alternative explanation–the position of the bones could be attributed to human butchers OR natural predators scattering the bones.  None of the new reports go into the details of why this might be considered a human-killed specimen.  Were stone tools found associated with the bones?  Are butcher marks on the bones?  Did they find animal gnaw marks?

A detailed description of the specimen hasn’t been published in the scientific literature yet, as far as I know.  The area was a lake during the late Pleistocene, and the mammoth may have been stuck in the mud when it was killed.  I would be interested in the stratigraphic context, but I’ll probably have to wait until the important details are published in a journal.  (I did send the archaeologist an email, asking him for more details.  I’ll post his response, if he sends me one.)

The news reports reveal the confusion of the original reporter.  More than 1 report mentions that this specimen was a subspecies of mammoth.  Obviously, many of the articles were simply copied verbatim from information reported in someone’s original report. (In other words…plagiarized)  I think this journalist was under the mistaken impression that the Columbian mammoth was a subspecies of the woolly mammoth (Mammuthus primigenius).  This is incorrect.  The Columbian mammoth was a distinct species, though recent genetic evidence, along with old anatomical studies, show the 2 species interbred where their ranges overlapped.  (See: https://markgelbart.wordpress.com/2016/02/18/the-southern-and-northern-range-limits-of-the-columbian-mammoth-mammuthus-colombi/ )

Hopefully, a scientific journal will publish a paper about this species because the news reports are just so inadequate.

Pleistocene Fossils and Nazi Soldiers Buried in Latvia

September 13, 2016

About 30 years ago I took a business class at Augusta College that revealed 1 of my most disappointing shortcomings.  The professor separated us into groups of 7, and we were assigned topics for discussion everyday.  After several weeks of discussions the professor told us to rank group members in order of most to least influential.  I ranked myself 3rd and felt it was a fair assessment.  But I ranked 6th in the overall average of everybody’s rankings.  Much to my astonishment, I was ranked well behind a guy (that I ranked last) who often showed up to class tripping on acid and had not spoken 1 word during the entire assignment.  It was then when I first realized I had no influence, and I felt so depressed I almost cried.  It explained why I had such a hard time getting women to go on dates with me.  It explained why ridiculous jerks who continuously misused and abused women could get any dates they desired, while I was lucky to get a condescending rejection, if the woman even acknowledged my attention at all.

Now that I am older, I’ve learned to accept the reality that I have little influence or charisma.  I am “low key” as 1 of my former supervisors reported in a complimentary job evaluation.  I even take solace in the knowledge that some of the most influential people in history are considered monsters.  I’ve recently been re-reading The Rise and Fall of the Third Reich by William Shirer–the best history book I’ve ever read. The details of how Hitler completely took over a country amaze me.   Adolf Hitler was clinically insane.  A psychiatrist diagnosed him with manic-depressive psychosis, now known as bipolar disorder.  (The Nazis eventually killed the doctor and made it look like a suicide.)  Yet, he was easily the most influential man of the 20th century.  He drastically changed the course of history after becoming the dictator of Germany with the legal power of life and death over every citizen there and in all the territories conquered under his rule.  He even replaced the customary salutation of “hello” and “goodbye” with “Heil Hitler.”  He is responsible for the deaths and misery of millions of people.  So if anybody ever criticizes me for having no influence or lacking charisma, I can always tell them, “well, you know who DID have a lot of influence?…Adolf Hitler.”

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I’m a nice guy, but I have no influence.  Hitler…not a nice guy…was the single most influential man to live during the 20th century.  I used to feel sad about my lack of charisma, but when I think about this, I don’t feel as bad.

My late father survived the holocaust in Buzcazc, Poland.   One day, the Nazis ordered all the adult Jewish men to the town soccer stadium.  My grandfather decided not to obey that order, although he considered it.  That night, my father’s family heard shots from the direction of the soccer field and a few minutes later, an athletic man who ran and escaped, told them the Germans lined up and shot all the Jewish men in attendance.  Shortly after this incident, my grandfather paid a Ukrainian farmer to hide his family in an hayloft.  There, 6 people lived on a very low calorie diet for 2 years before they were liberated by the Russian army.  However, all of my father’s grandparents, uncles, aunts, and cousins were killed in concentration camps or shot upon initial confrontation.  My father always liked to watch WWII movies because they depicted the killing of Nazis.  Until his death, he never tired of watching “killing Nazis”–his term for his favorite war movies.  My dad would have enjoyed a movie about the Russian military campaign in Latvia during 1944 that occurred to the north of where he was liberated, but Hollywood has yet to depict this battle.  The Russians trapped 350,000 German soldiers here.  They killed 100,000 and captured the rest.  All of the bodies were buried near where they were killed, and the blue clay soil helps preserve the Nazi skeletons and artifacts that litter the subsurface of the Latvian countryside.

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Location of Latvia.  The Russian army trapped 350,000 German soldiers here.  100,000 were killed and buried on the battlefields.  In many rural areas live humans are outnumbered by buried German corpses.

Rural Latvia is an economically depressed region and most of the people who lived there moved to the city or to other European countries.  So in many places, Nazi corpses outnumber live people.  The old poor alcoholics who remain often dig up Nazi graves and sell the artifacts for cash.  German army dog tags sell for $60.  SS dog tags sell for several hundred dollars.  An helmet can fetch $90.  The market for Nazi artifacts is strong and can be lucrative.  According to Bloomberg Businessweek,  “Herman Goering’s sweat-stained uniform” sold for $126,000.  An orthodox Jew bought Josef Mengele’s diary for $245,000.

The same properties in Latvian soil that have preserved Nazi skeletons also saved paleoecological evidence dating to the Pleistocene.  Stratigraphic cores reveal evidence of past fluctuations in climate alternating between temperate, cold, and full glacial.  Pollen analysis shows a forest of elm, basswood, and hazelnut predominated during warm interglacials.  Immediately before and after glacial maximums the environment consisted of grassy steppe with pockets of birch, alder, spruce, and pine.  Glaciers have entirely covered Latvia during the glacial maximums of the numerous Ice Ages that occurred over the past 2-3 million years.  Over 40 specimens of mammoths have been excavated in Latvia (impressive for such a small little studied area), and caribou remains are common as well.  A Latvian can dig in their backyard and find Nazi skeletons, and if they keep digging deeper, they might find the remains of a mammoth too.

References:

Rogers, Thomas

“The Bodies”

Bloomberg Businessweek   September 4, 2016

Zeles, Vital; Maris Nartiss, and Tomas Satir

“Pleistocene Glaciation in Latvia”

In   Quaternary Glaciation–Extent and Chronology: a closer look

Edited by J. Ehles, P.L. Gillard and P.D. Hughes

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The Mysterious Decline of the Eastern Spotted Skunk (Spilogale putorius)

September 6, 2016

I was delivering newspapers on Sand Bar Ferry Road in Augusta, Georgia on the only occasion I’ve ever seen a live spotted skunk.  In the 26 years since that 4 am encounter, I’ve driven by maybe 2 road-killed specimens on I-20 between Augusta and Atlanta.  The eastern spotted skunk is a rare animal, though it has a wide range from southern Canada to Florida and west to the prairie states.  But it has not always been as uncommon as it is today.  Like other small carnivore/omnivore species such as opossum, raccoon, and fox; it adapted well to European modification of the wilderness.  They benefitted from the elimination of larger predators, and the creation of edge habitat between forest and farmland.  Formerly, spotted skunks could often be found in burrows under barns and hay stacks where they hunted their favorite prey–mice.  Until the 1940s trappers killed over 100,000 annually in some states.  However, within a 3-5 year period spotted skunk populations declined by 90% and have never recovered.  Scientists don’t know why.

Spotted skunk demonstrating its warning handstand.

Spotted skunk doing a handstand.  If you see one doing this, flee the area…it’s about to spray.

Scientists suspect many causes in the spotted skunk population decline but none fit the timing or align with the known facts.  Modernization of farming techniques is 1 suspected cause.  Modern farmers expand cultivated fields and eliminate natural border areas, and they consolidate barns.  This does infringe on spotted skunk habitat.  However, agricultural modernization has been a long term process, and the decline of the spotted skunk occurred rapidly.  Pesticide use is another suspect because insects are an important item in the spotted skunk’s diet.  But widespread use of pesticides began after the decline of spotted skunk populations.  Scientists looking at the data can’t “fully implicate” over trapping as the culprit in the decline.  They also can’t find a definite correlation with any diseases.  Most small animals respond cyclically to disease outbreaks, but eventually inherited immunity among some individuals allows their numbers to bounce back.  Spotted skunk numbers never recovered from their sudden decline.  The mink enteritis virus spread throughout mink farms in the 1940s, so this is 1 possible disease that may have devastated spotted skunk populations.  Still, they should have recovered by now.

I propose diseases spread by feral or domestic cats may play a role in keeping spotted skunk populations depressed.  Skunks and house cats are known to interact in a friendly manner.  They even play together, and skunks will often feed on the food left outside for cats.  Because cats are so numerous, they are more likely to have stronger immune systems and can survive diseases that the far less common skunks are susceptible to.

Video of a cat playing with 2 wild baby skunks.  House cats and skunks get along well together.  I hypothesize diseases carried by cats depress skunk numbers.

The spotted skunk is listed as a species of conservation concern.  Unfortunately, it receives little attention because it is…just a skunk.  This is a shame.  The spotted skunk is a neat little mammal, usually weighing less than 3 pounds.  It is more acrobatic than its larger, more common cousin, the striped skunk (Mephitis mephitis).  It can climb trees and when it is threatened it stands on its front paws and can accurately spray from 10 feet away.  This species is little studied.  One of the few studies of spotted skunks (in the Oachita Mountain National Forest, Arkansas) determined they prefer closed canopy forests with dense undergrowth.  The dense undergrowth keeps them hidden from their most dangerous predator–the great horned owl.  Ironically, the habitat they prefer is the opposite of what wildlife managers are aiming for here.  Wildlife managers are using prescribed fire to create open short leaf pine forests with grassy understories where spotted skunks would be vulnerable to predation.

The spotted skunk has a long evolutionary history in North America.  It likely descended from a late Pliocene ancestor known as Spilogale rexroadi over 2 million years ago.  Fossil remains of Spilogale putorius dating to the Pleistocene have been excavated all over North America including a specimen recovered from Ladds Mountain in north Georgia.  I hope this species can survive in the future from the scourge of the cat diseases or whatever problem(s) ails it.

References:

Gompper, Matthew; K. Hackett

“The Long Term, Range-Wide Decline of a Once Common Carnivore: the Eastern Spotted Skunk (Spilogale putorius)”

Animal Conservation May 2005

Lesmeister, Damon: Matthew Gompper, Joshua Millspagh

“Summer Resting and Den Site Selection by Eastern Spotted Skunks (Spilogale putorius) in Arkansas”

Journal of Mammalogy 2008

 

The Ecology and Evolution of Live Oaks (Quercus subsection virentes sp.)

September 2, 2016

The southern live oak (Quercus virginiana) is my favorite species of tree.  I love the sprawling canopy, usually covered in silvery-gray Spanish moss, and the way they grow in shady groves that cool off their native habitat–the hot sea islands and lowlands of southeastern North America.  The southern live oak is specially adapted to grow on the edge of maritime forests where their sturdy limbs can reach over adjacent fresh or saltwater marshes.  Before Europeans modified the environment, most live oaks occurred on the edges of watery habitats.  Unless a natural gap occurred within the forest, the limbs of most individual trees sprawled in one direction over water, enabling them to capture sunlight that other species of trees couldn’t reach.  But man cleared the original maritime forests and replanted live oaks in groves where the limbs of widely spaced trees could sprawl in all directions.  The limbs evolved to withstand strong sea winds, and when Europeans first colonized the region they were quick to make use of the solid wood for ship-building.  Today, the tree is planted as an ornamental, and its abundant acorn production feeds wild hog, deer, squirrel, and other wildlife.

There are 7 species of live oaks including the southern, the sand (Q. geminata), the dwarf or runner (Q. minima), the Cuban (Q. sagraeana), the Texas (Q. fusiformis), the Baja (Q. bradegeei), and the encina or Central American (Q. oleoides).  All of these species grow at low elevations in well drained soils.  They are evergreen trees that require cross pollination.  Live oaks will occasionally hybridize with other species of white oaks and with other species of live oaks in ranges where they overlap.  The genetic evidence suggests white oaks first evolved 28 million years ago, and the live oak group (a subsection within the white oak family) diverged from other white oaks 11 million years ago.

The Seven Sisters live oak in Mandeville, Louisiana is the largest and oldest known live oak in the world. It is estimated to be 1500 years old.

Sand Live Oak (Quercus geminata) in a stand of open pine savannah.  It is more fire tolerant than Quercus virginiana.

Dwarf Live Oak shown as a small group growing and expanding naturally via underground stems/roots

Dwarf live oak (Q. minima).  This species is fire dependent.  Its root system is much larger than the shrub itself.

The ranges of southern, sand, and dwarf live oak overlap; but they don’t hybridize often because they flower at different times and they prefer different habitats.  The southern live oak is a large tree that is fire intolerant.  This species can only grow successfully in environments where it is protected from fire such as islands surrounded by salt marsh and inlets or hardwood hammocks surrounded by swamp.  The sand live oak is fire tolerant, and it can grow in pine savannahs subject to frequent fire.  The runner live oak is a small shrub that is fire dependent.  It has an extensive root system underground and will re-sprout after a ground fire, but it can’t grow in shade.

Scientists believe live oaks evolved in southern North America because most species are frost tolerant.  The encina or Central American live oak lost this frost tolerance after it colonized the tropics.  The genetic evidence suggests the Cuban live oak is derived from the Central American species, but scientists don’t know how the ancestor of the Cuban species made it to the island.  Acorns likely rafted across the Caribbean protected from the salt water in a clump of vegetation.

The genetic evidence suggests the ancestor of the Baja live oak was formerly much more abundant, but the opening of the Sea of Cortez isolated this species.  It shared a common ancestor with the closely related Texas live oak.

Reference:

Cavender-Bares, J.; et. al.

“Phylogeny and Biogeography of the American Live Oaks (Quercus subsection virentes); a Genomic and Population Genetics Approach”

Molecular Ecology 24 2015

 

 

A New Study of Pleistocene Lion (Panthera spelaea) Genetics Confirms it was a Distinct Species

August 29, 2016

A couple of my readers brought 2 new studies of lion genetics to my attention.  One of the studies confirms the notion that the extinct Eurasian lion (Panthera spelaea) was a distinct species from the present day African lion (Panthera leo).  (See: https://markgelbart.wordpress.com/2012/05/02/three-pleistocene-lions-were-they-distinct-species-or-the-same-animal/ ) The scientists who co-authored this study analyzed the DNA from 2 ~30,000 year old specimens of “cave” lions and used it to compare with the DNA of other felid species.  They extracted the DNA from a lion arm bone found in Yukon, Canada and some lion hair preserved in Siberian permafrost.  The study suggests Panthera spelaea and P. leo were sister species that diverged ~1.89 million years ago.  This divergence precedes the oldest known lion fossil by over 1 million years.  Panthera fossilis, an extinct archaic species of lion, was thought to be ancestral to both P. spelaea and P. leo.  However, this species lived 700,000 years ago, and the divergence likely occurred before P. fossilis evolved.  Fossils of a cat in the panthera genus that date to 3.5 million years ago have been found in Africa, but not enough skeletal evidence exists to narrow it down to species level.  P. spelaea certainly evolved a greater physiological adaptation to colder climates at the beginning of the Pleistocene as periodic Ice Ages became more severe in Eurasia.  This physiological difference may explain the speciation event that separated P. spelaea from P. leo.

Although this study didn’t examine Panthera atrox, the species of lion that occurred across North America south of the Cordilleran Glacier, the results do make it seem more likely that it too was a different species.

Specimens used in the below referenced study–a lion arm bone found in the Yukon and a hair sample found in Siberian permafrost.

The other study looked at the genetics of present day lions living in Africa and India.  This study determined there are 6 distinct regional breeding populations of lions–the west, central, northwest, northeast and south Asian, east/southern, and southwest.  These breeding populations have been repeatedly isolated from each other because of altered landscapes influenced by cyclical Pleistocene climate changes.  Lions prefer open savannah habitats but avoid thick tropical jungles and large deserts.  A belt of monsoons currently brings heavy rain to west central Africa, but this monsoon belt shifts every ~21,000 years, changing the zones of tropical forests and deserts.  Populations of lions become isolated from each other when their favored savannah habitat fragments and is separated by forest and desert.  Other species of savannah habitat show similar intraspecific genetic isolation including giraffe, water buffalo, bushbuck, waterbuck, hartebeest, warthog, cheetah, and spotted hyena.

The common ancestor of all present day clades of African lion diverged ~245,000 years ago.  The genetic evidence suggests all clades of lions were relegated to small refugia during the Last Glacial Maximum when much of Africa hosted landscapes unsuitable for the big cats.  Humans have recently translocated lions from different regions into other regions in an attempt to rebuild populations.  This interference results in the crossbreeding of different clades with each other.  Zoo lions are also crossbred clades for the most part.

References:

Barnett, Ross; et. al.

“Mitogenetics of the Extinct Cave Lion, Panthera spelaea, Resolve its Position Within the Panthera Cats”

Open Quaternary June 2016

Bertoli, L.S.; et. al.

“Philogeographic Pattern in Africa and High Resolution Delineation of Genetic Codes in the Lion (Panthera leo)

Scientific Reports May 2015

 

Salt Domes of Texas and Louisiana

August 25, 2016

Salt domes are fascinating geological structures of ancient origin.  Over 500 subsurface salt domes have been mapped in Texas, Louisiana, and Mississippi.  During most of the Mesozoic Age from 150 million years BP to 65 million years BP a shallow inland sea covered this region.  The Western Interior Seaway periodically dried, leaving vast salt deposits.  Later, when the ocean re-filled the basin; loads of sediment, sea shells, and coral reefs were deposited on the layers of salt.  Sedimentary rocks such as sandstone, shale, and limestone formed from these deposits.  Meanwhile, organic rich mud buried under these layers was transformed into petroleum.  On the surface of the earth salt is a solid crystal.  But deep underground where it is heated and under high pressure, salt becomes malleable–like toothpaste.  All those miles of sedimentary rock squeeze the salt upward (and sometimes sideways and downward), not unlike an hand squeezing a tube of toothpaste.  This process explains the shape of salt domes.

The top of salt domes comes into contact with ground water.  The chemical reaction of ground water + salt dome creates cap rock, consisting of sulfur, calcite, gypsum, and anhydrite.  Miners extract and process these materials because they have wide industrial and agricultural uses.  The structure of sedimentary rocks on the edge of the salt domes often trap petroleum, so oil wells are drilled adjacent to them as well.

salt domes of the East Texas Basin

Illustration of subterranean salt domes in Texas.

Illustration of a typical salt dome.  They often trap petroleum deposits.

Cattle grazing on top of Damon Mound, an above ground salt dome located in Texas.

Cretaceous Western Interior Seaway

A shallow sea existed over Texas and Louisiana during the Mesozoic.  It repeatedly dried out, concentrating vast amounts of salt.

Although there are hundreds of known subsurface salt domes in the region, just an handful breach the surface.  Damon Mound in Texas (near Houston) is an example of an aboveground salt dome.  It rises 80 feet above the surrounding coastal plain.  Avery Island, Louisiana is another aboveground salt dome.  It is a forested hill, surrounded by salt marsh.  The cap rock here contains Pleistocene-aged sediments where the remains of prehistoric mammals including mammoth, mastodon, Harlan’s ground sloth, Jefferson’s ground sloth, horse, and bison have been excavated.  The Mcilhenny family grows tobasco peppers on Avery Island for their famous hot sauce.  Hugh Mcilhenny, founder of the company, discovered some of these bones after the Civil War.  He kept them on display but the specimens were lost after his death, then later re-discovered by 2 professors.  Some were sent to the Smithsonian Museum and others were sent to LSU and Tulane.  In 2012 they were returned to Avery Island where they are available for display upon request.

The Inner Space Cavern Fossil Site near Georgetown, Texas

August 18, 2016

Construction workers building an highway bridge over a railroad line accidentally discovered Inner Space Cavern in 1963.  This site is located on the edge of the Edward’s Plateau 1 mile south of Georgetown, Texas.  The eastern side of the Edward’s Plateau is a hilly landscape sitting on Cretaceous-age limestone bedrock.  Rain dissolves limestone creating many underground caves in the region.  The workers drilled down 33 feet and when the drill bit reached the cavern it fell an additional 24 feet becoming lodged in stalagmites.  Inner Space Cavern is also known as Laubach Cave, named after the family who owns the land.  The Laubachs opened up an accessible entrance to the cave, and it is now a tourist attraction.  The cave is underneath the rail line and Highway 35.  Skeletal remains of late Pleistocene age vertebrates have been excavated from 5 sites in the cave.  However, radiocarbon dating of these specimens was executed during the late 1960s and early 1970s when this technology was still in its infancy, and the resulting dates are not considered accurate.  The specimens are at least 13,000 years old, but it’s unclear if they can even be radiometrically dated.

Location of Georgetown, Texas

Location of Georgetown, Texas.  Inner Space Caverns is just south of this town.

Inner Space.

View inside Inner Space Cavern.

An unique assemblage of grazing fauna roamed central Texas during the late Pleistocene.  Mammoth, bison, horse, camel, glyptodont, and a large extinct species of pronghorn (Tetrameryx shuleri) occupied the plains.  The fossil record suggests Tetrameryx shuleri was restricted to what is now the state of Texas during the late Pleistocene.  Because it was a regional species, it was more vulnerable to extinction when man colonized the area.  A single specimen of the scimitar-toothed cat (Dinobastis serum) was found in Laubach Cave.  Although this species ranged widely over North America, the distribution of its remains suggests the region from Texas and Oklahoma to western Tennessee may have held a core population.  Other large mammal remains found in the cave include Jefferson’s ground sloth, deer (probably white tail rather than mule), flat-headed peccary, jaguar, dire wolf, and the extinct Florida spectacled bear (Tremarctos floridanus).  This is the westernmost known occurrence of the Florida spectacled bear during the late Pleistocene.

Today, the Texas kangaroo rat (Dipodomys elator) is restricted to 10 counties in north Texas bordering Oklahoma.  Remains of this species found in Laubach Cave show it formerly ranged further south.  Black-tailed prairie dogs (Cynomys ludovicianus) and meadow voles (Microtus pennsylvannicus) also no longer occur this far south.  Short-tailed shrews (Blarina carolinensis) don’t live this far west any more.  The presence of these small mammals suggests the climate in this region was wetter with cooler summers during the Ice Age than it is today.

Texas kangaroo rat (Dipodomys elator).  Skeletal remains of this species dating to the late Pleistocene were found in Inner Space Cavern.  It no longer occurs this far southeast.

Skeletal remains of this extinct pronghorn (Tetrameryx shuleri) were found in Inner Space Cavern.  This was its easternmost known occurrence. Note the 4 prongs.

Evidence from Inner Space Caverns shows the extinct Florida spectacled bear (Tremarctos floridanus) lived as far west as central Texas.

The faunal composition of Laubach Cave indicates this region during the Ice Age was dominated by grassy plains but with some riparian woodlands and mesquite/acacia scrubland.  Grazers such as mammoth, horse, and camel clearly are evidence of prairie habitat.  The presence of Jefferson’s ground sloth, deer, cottontail rabbit, spectacled bear, and jaguar (an ambush predator)  make it seem likely that finger shaped communities of trees grew alongside rivers and creeks.  These riparian woodlands probably consisted of centuries old live oaks, cottonwoods, and sycamores.  Flat-headed peccaries, jackrabbits, and kangaroo rats prefer (or in the case of the extinct species, preferred) scrub habitat.  Texas kangaroo rats almost exclusively burrow beneath the roots of mesquite.

Vegetation of this region was similar to that of today, yet slightly different.  The moderate increase in precipitation combined with cooler summer temperatures meant deeper top soils and greater stream flow through rivers.  The alternate climate caused changes in the abundance and density of some species of plants.  Prairies were mixed with some tall grass and some shortgrass, depending upon the topography.  These prairies, like many other natural communities, were thick with wildlife until man came along.

Reference:

Sansom, Jones; and Ernest Lundelius

“Inner Space Cave: Discovery and Geological and Paleontological Investigation”

Austin Geological Society Bulletin 2005

If I could Live During the Pleistocene Part 13–Making Insecticide from Tobacco

August 15, 2016

This is the newest installment of an irregular series I write for this blog about my favorite fantasy.  I daydream that I traveled back in time to east central Georgia 36,000 years ago where I enjoy a life of self-sufficiency but with modern conveniences. (See: https://markgelbart.wordpress.com/category/if-i-could-live-during-the-pleistocene/ ) In my fantasy world I have a farm surrounded by a high stone fence that keeps mastodons and bears from raiding my garden and orchard, but it recently occurred to me this wall wouldn’t stop insect pests.  As an experiment in my real world yard, I planted peach trees from seed.  Most fruit sold in grocery stores comes from mutated varieties grafted on root stocks because fruit trees don’t produce the same quality from seed, but peaches reportedly are an exception.  Some sources claim peaches grow true to seed, while others say peaches grown from seed are inferior.  My peach trees started to bear this year, and the ones I salvaged tasted as good as farmer’s market peaches.  Unfortunately, most of the peaches fell off or were ruined because of an insect pest known as plum curculio (Conatrachelus nenophar), a little beetle in the true weevil family.  This experience made me realize I needed to revise my fantasy and make my own insecticide, if I want to have fruit at my Pleistocene homestead.  In the modern world I can buy the most delicious local peaches, nectarines, and plums; but I won’t have any fruit in the Pleistocene without spraying.

This is one of my least damaged peaches.  Most of the others fell off long before they ripened.  In some localities spraying fruit is necessary.

I won’t spray until after the petals fall off because I don’t want to poison the butterflies and bees that pollinate the flowers.

plum curculio

Plum curculio.  This species of beetle destroyed all of my peaches.  It is abundant in my neighborhood probably because of the presence of wild plums and cherries.

Plum curculios are common in areas with wild plum and wild cherry trees.  They readily adapted to fruits introduced by Europeans, especially peaches.  The adult females burrow into unripe fruit and make a crescent shaped hole where eggs are deposited.  The crescent shape keeps the larva from being crushed when the fruit grows.  Most fruit falls off the tree, and any fruit that ripens is blemished so badly it can’t be sold.  The trees must be sprayed as soon as the flower petals fall and again when the fruit is in the shuck stage.

 

 

 

 

 

 

 

Tobacco plants.

It is easy to make insecticide from tobacco (Nicotiana tabacum).  Tobacco is in the nightshade family, a group of plants that evolved the ability to produce toxins in their leaves.  These poisons prevent insects and other animals from consuming the leaves.  To make insecticide mix 1 cup of dried tobacco leaves with 1 gallon of water and let it sit in the sun for 24 hours.  Then add 3 tablespoons of liquid soap.  (Just think: people who smoke cigarettes are smoking insecticide.)  The nicotine in tobacco destroys an insect’s nervous system.

I’d have to grow tobacco in my Pleistocene world, but I wouldn’t smoke it.  I prefer marijuana.

 

The Nature of Trials of the Earth by Mary Hamilton

August 10, 2016

One of the last great stands of wilderness in eastern North America existed along the Mississippi River during the late 19th century.  Loggers ruined this environment between 1880-1910, but in Mary Hamilton’s autobiography, Trials of the Earth, she described the awesome nature of this region.  Though her book focuses on her personal life and all the tragedies and hardships her family endured, I collected all of the interesting tidbits of natural history that she wrote about.

A fascinating book about the pioneer life of a woman in Mississippi and Arkansas during the turn of the 19th century.

In 1896 Mary Hamilton, along with her 2 young children and her brother and sister, followed her husband to a logging camp on Concordia Island, Mississippi.  The island was bound by a chute of the Mississippi River and the main channel.  Her husband was a supervisor at the camp, and he was too busy to bring her himself.  Instead, he marked a wagon trail through the wilderness, and a guide (actually an inexperienced teenaged boy) helped her find the camp where she eventually worked as a cook for 30 lumberjacks.  She was accustomed to this work, having boarded over 100 lumberjacks at a previous camp.

The family settled in a big white tent.  The island consisted of a dense forest of large mature oak, sweetgum, hackberry, and tulip trees with a thick undergrowth of bamboo cane that grew all the way to the lower limbs of the tall trees.  (See: https://markgelbart.wordpress.com/2013/01/28/canebrakes-are-forlorn-landscapes/)  Closer to the river, the forest thinned out, probably because of frequent flooding, and enormous sycamores and cottonwoods grew here.

The lumberjacks felled the trees and lashed them together in rafts to be tugged down the river to sawmills.  Some species of trees float, while others sink, so the lumberjacks had to lash “floaters” with “sinkers.”  Sweetgum and oak sink and had to be lashed to cottonwood, ash, or cypress.

Some species of trees sink, while others float.  Lumberjacks had to lash logs from “floaters” with logs from “sinkers” when they sent them downstream to the mills.

This is how people with wagons crossed rivers before bridges were built.  People who owned the ferry charged for its usage.

Mary’s younger brother was an accident prone Gomer Pyle type, and her husband was afraid he would hurt himself or somebody else, if they put him to work as a lumberjack.  Therefore, they assigned him the task of hunting and fishing to supplement their supplies.  It was difficult to supply this camp with food.  During times of high water, wagons couldn’t reach the camp, and supply wagons occasionally got lost in the wilderness and never arrived.  Sometimes the man in charge of the supply wagon ignored the grocery list and bought candy and cakes instead of the staples they needed.  So hunting was useful.  Deer and black squirrels were abundant.  Apparently, the black phase of the fox squirrel (Scirius niger) was the only species of squirrel on this island.  This surprises me because gray squirrels (Scirius carolinensis) prefer the kind of dense forest Mary describes.  In the south fox squirrels generally prefer more open woodlands.

Black phase of the fox squirrel.

One day Mary’s brother encountered a mother bear playing with her cubs.  He threw down his gun and ran for his life, yelling “there’s a dozen lions after me.”  Bears were plentiful on the island, and the lumberjacks’ diet here included bruin along with local beef and pork (wild hogs ran wild everywhere) and corned beef from New Orleans.  Animals took advantage of the lumber camp as a source of food as well.  A bear stole a quarter of a beef left to hang outside one night.  Raccoons, opossums, and bobcats fought over the camp garbage every night, and Mary heard panthers screaming and wolves howling nightly.  Later, when her family moved to an homestead on the nearby Sunflower River she insisted her husband shine the lantern on her when she went outside to bring in the laundry every night  because she heard a panther screaming regularly on both sides of the river.  People didn’t know much about panthers and wolves then and were very afraid of them. Mary didn’t consider all nature unpleasant.  She liked to hear the birds and frogs in the spring, and one day she collected 5 gallons of blackberries the size of Guinea hen eggs.  The rich delta soil produced berries larger than modern cultivated ones sold in farmer’s markets.

Mary’s husband built a “freshwater shrimp” trap for her brother.  The trap worked and captured bags of “shrimp” everyday, but her brother didn’t know “shrimp” meant crawfish.  He always threw away the crawfish until he was informed of his ignorance.

The Mississippi River shifted direction during their time on Concordia Island.  This caused a near disaster.  The river started eroding the bank overhanging all the rafts of lumber.  The rafts could have become covered in sediment and lost.  They immediately sent for tugboats that hauled the floating rafts and most of the logs were saved.  This event, referred to as “sloughing,” must have been an impressive sight.  Trees fell into the river, and the sediment collapsing made a “boom, boom” sound.

Next, Mary’s family moved to a lumber camp near the Sunflower River, a tributary of the Yazoo.  This region too was all canebrake and woods where panthers screamed and wolves howled every night.  Getting water at this camp was laborious and difficult.  Iron pipes were driven into the ground to reach well water, but oftentimes this was hard water high in magnesium and calcium.  Hard water is safe for drinking but can’t be used for washing dishes or clothes.  Mary softened the water by adding lye made from wood ashes.  The addition of a base binds the calcium and magnesium ions, making the water usable for cleaning.  Too much water became a bigger problem at this camp.  Rainy weather flooded all the surrounding bayous, isolating the camp from civilization, and they ran short of food.  They realized the rising water was going to completely inundate the camp and the wooden clapboard house where they were living.  So Mary’s husband cut a path through a canebrake that led to an Indian mound located above the floodplain, and he built a small boat.  The boat wasn’t big enough for all of them, and he had to make 2 trips to save his wife and 3 children.  Mary waited with her 5 year old daughter and infant son for 6 hours, while her husband carried their other small child to safety and returned.  She spent all this time standing on a chair on the highest ground, holding her baby and comforting her young daughter.  The baby slept the entire time, despite the rain.  She saw a bear, deer, rabbits, mice, and snakes swimming by them, looking for high ground.

Tornadoes often storm up the Mississippi River valley, then turn inland and smash through forest.  Mary describes one such area that was known as “the cyclone,” an area estimated to be at least 36 square miles.  “The cyclone,” located near the present day site of the Parchman State Penitentiary, was an eerie landscape without a single standing tree.  Instead, the ground was littered with fallen timber covered in grapevines, poison oak, and thorny brier bushes.  Ecologists call these environments windthrows.  This windthrow was on rich soil and hosted luxuriant tangles of vegetation, making the area impassable.  Mary tells the story of a well-liked Jewish paymaster who chose to take a shortcut through “the cyclone” rather than travel the 5 mile path around it.  He was bringing the pay to a neighboring lumber camp.  He got lost for 4 days and went half-mad from panic and dehydration.  The thorns tore all his clothing off as he scrambled through the briers.  Search parties failed to find him.  He finally wandered close to the camp, completely naked and incoherent but with the money in his hand.

Mary Hamilton described an area near the present day site of Parchman Penitentiary as “the cyclone.”  It was a windthrow of at least 36 square miles covered in an impenetrable stand of vines, briers, and cane.

Mary worked hard most of her life, but shortly after she married she did enjoy a bit of a vacation in Missouri where she stayed with friends by the Castor River.  Here, she learned how to fish.  She mostly caught bass, but on one early morning before anyone else was awake she caught an eel.  This sent her screaming in terror back to the house.  She was so scared she didn’t let go of the rod and carried the eel to the front door.  Mary wanted to get rid of it, but her husband was from England where eel is considered a delicacy, and he prepared it for supper.  One kind of fish that Mary caught here was referred to as a “white salmon.”  It took a little research, but I determined her “white salmon” was actually a walleye (Sender vitreus).  The old Ozark term for walleye is “jack salmon.” 

Mary caught bass, an eel, and walleye (which she called “white salmon”) in the Castor River.

I’d like to live in a wilderness where panthers scream and wolves howl every night.  And it would be rewarding to live off the land, gardening and raising animals for food.  But I wouldn’t want to do this without modern conveniences.  Mary worked from dawn to past dusk for most of her life.  I envy the wilderness she got to see but not the hard life she endured.