Archive for the ‘geology’ Category

The Most Cataclysmic Ice Age Floods

February 11, 2017

Climate patterns were different during Ice Ages.  The Rocky Mountain region of North America is mostly arid today, but more precipitation and lower rates of evapotranspiration led to the formation of vast lakes during cooler climate phases.  Most of these lakes gradually disappeared in non-dramatic fashion after the climate became warmer and drier.  Evaporation changed the former sites of these freshwater lakes into empty basins, salt plains, and much smaller salt lakes.  But the demise of Glacial Lake Missoula caused a spectacular flood, perhaps the largest deluge in earth’s history.

A southern lobe of the Cordilleran Ice Sheet blocked the flow of the Clark Fork River near the border of present day Idaho and Montana, creating a glacial lake as big as Lake Erie and Lake Ontario combined.  At times it was almost 2000 feet deep, though it periodically lowered and partially drained.  The ice dam itself was an astonishing 2000 feet high.  The warm climate phase that marked the end of the Ice Age beginning about 15,000 years ago melted the ice dam, and the tremendous volume of water in Lake Missoula burst across Idaho and eastern and central Washington, finally emptying through the Columbia River valley into the Pacific Ocean near the present day town of Astoria, Oregon.  This massive flood created a landscape known as the “channeled scablands.”  The geological formations that serve as evidence of this cataclysm are impressive and picturesque.

Areal Scenario Map of the Ice Age Floods - Click to View Larger Image

The largest floods in the history of North America occurred in the Pacific northwest following the end of Ice Ages.

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These geological landforms were caused by post Ice Age floods.

Below is a link to many more photos of these formations.

http://hugefloods.com/Scablands.html

The flood carried large boulders encased in icebergs.  These “erratics” can be found throughout the channeled scablands.  There are dry falls–350 foot tall hills under where 300 feet of Lake Missoula water formerly flowed in what were temporary waterfalls.  Huge ripple marks can be seen on Camas Prairie.  Other amazing formations are the kolk potholes where swirling eddies gouged out deep troughs.  Strandlines and lake deposits visible on the sides of mountains are evidence the dissolution of glacial lakes occurred repeatedly in this region–perhaps more than 34 times during the Pleistocene.

The scouring of these intermittent Ice Age floods eroded most of the topsoil in this region and much of the scabland is unsuitable for crops.  But there are some exceptions.  The tops of some hills were above the flood and still have enough soil for growing crops, and some soil eroded from mountains into some valleys where crops can also be grown.  But for the most part agricultural activity here is limited to livestock grazing.

Humans began colonizing North America about the same time this cataclysmic flood occurred. Any people in the path of the deluge perished.  Members of the sparse population living on the edge of the flood witnessed an unusual, awe-inspiring event, a story they likely told their children and grandchildren.  It may be the origin of ancient flood myths found in Native American lore.  Flood myths are known in cultures worldwide and probably are based on inherited memories of local floods that occurred at the end of the Ice Age when glaciers melted and sea level rose rapidly.

Reference:

Smith, Larry

“Repeated Sedimentation and Expanse of Glacial Lake Missoula Sediments: A Lake Level History of Garden Gulch, Mountain, USA”

Quaternary Science Review January 2017

The Pleistocene Champlain Sea

December 22, 2016

The weight of a glacier depresses the earth’s crust, a geological process known as crustal downwarping.  The Laurentide Ice Sheet covered most of eastern Canada during the Last Glacial Maximum, but a sudden warm phase of climate led to the rapid recession of its southern lobe.  About 13,000 years ago ocean water flooded into this glacial depression located in the present day region of eastern Quebec and Vermont, creating the Champlain Sea. The transgression of ocean water into land recently depressed by a glacier is termed eustatic sea level rise.  The Champlain Sea was bordered on its northern edge by melting ice cliffs formed by the retreating glacier, while a marshy tundra existed on its south side.  Over time this tundra was colonized by spruce trees.  This boreal forest was in turn replaced by a landscape of mixed conifers and northern hardwoods.  Meltwater and falling chunks of ice from the glacial cliffs reduced the salinity of the Champlain Sea, making it a brackish estuary teaming with a rich diversity of marine life.

Map of the pre-historic Champlain Sea.  It was created by crustal downwarping and fed by melting glaciers.  Ocean water flooded into this basin via the St. Lawrence River.  Isostatic rebound terminated the existence of this sea.

Lévis is located in Southern Quebec

Location of Levis, Quebec.  An excellent fossil site is found in the St. Nicholas borough of this city, containing many species that lived in the defunct Champlain Sea.

The fossil record suggests the white whale ( Delphinapterus leucas ) was the most common large mammal living in the Champlain Sea.  The white whale feeds upon fish, cephalopods, and shellfish.  The presence of a large population of white whales indicates an abundance of fish, and this is corroborated by the remains of both fresh and saltwater species found in deposits dating to this age here, including cod, tomcod, eelpout, capelin, smelt, spoonhead sculpin, lake cisco, lake char, wrymouth, long-nosed sucker, lumpfish, 3-spine stickleback, sturgeon, and salmon or trout.  Humpback, finback, and bowhead whales, and harbor porpoises also frequented the Champlain Sea.  Harp and bearded seals bred on pack ice, ringed seals bred on the shore, and harbor seals swam in the open water.  Herds of walruses rested on the ice edge.  Scientists have even excavated the remains of birds here–long-tailed ducks, thick billed murres, common eiders, and arctic terns.  The foot bone of an old arthritic grizzly bear was found at St. Nicholas, the best fossil site in the region where the remains of many species were buried under tidal current sands.  Polar bears probably roamed along the shores, but fossil evidence of their presence here has yet to be discovered.Image result for beluga whale

Fossil evidence suggests white whales were the most common whale species in the Champlain Sea.

In 1849 geologists were surprised to find whale bones and the remains of marine invertebrates such as clams, scallops, mussels, barnacles, and sea urchin in landlocked Vermont, and it took them a while to determine a vast inland sea resulting from retreating glaciers was the explanation for the presence of these fossils.  The sea existed from about 13,000 BP to ~10,000 BP.  Saline levels often fluctuated, depending upon the varying quantities of meltwater, and the sea gradually became more shallow as the earth’s crust rebounded.  The rise of the earth’s crust following the retreat of a glacier is known as isostatic rebound–the opposite of crustal downwarping.  The sea also became warmer over time.  Arctic saxicoue was an early dominant clam, but eastern soft-shelled clams, a warmer water species, replaced them.

Eventually, isostatic rebound split the Champlain Sea into 2 freshwater lakes and blocked their outlets to the St. Lawrence River and Atlantic Ocean.  Lake Lampsilis, named after a common species of freshwater mussel ( Lampsilis radiati ), lasted until ~8,000 years BP, when isostatic rebound completely eliminated the basin that held the lake.  Today, Lake Champlain is a freshwater relic of what was formerly an enormous brackish sea.

Image result for champlain lake

Champlain Lake is a tiny remnant of the once vast Champlain Sea.

Reference:

Harrington, C. Richard; Marc Coornoup, Michael Chastia, Tara Fulton, and Beth Shapiro

“Brown Bear (Ursus arctos) (9880 BP) from Late Glacial Champlain Sea Deposts at St. Nicholas, Quebec, Canada, and the Dispersal History of Brown Bears”

NRC Press 2014

Heinrich Events Caused Annual Mass Whale Strandings during the Pleistocene and early Holocene

October 10, 2016

Despite the universal chorus of politicized alarmists, earth is currently experiencing a period of relative climatic stability compared to the dramatic climatic fluctuations that occurred during the Pleistocene.  The presence of vast ice sheets in the northern hemisphere contributed to this ancient climatic instability.  Glaciers blocked rivers, creating huge glacial lakes.  Warm spikes in average annual temperatures weakened the ice dams and caused breaches.  Massive outflows of frigid fresh water and icebergs periodically flooded into the North Atlantic, shutting down thermohaline circulation.  The gulf stream normally carries tropically heated water into the North Atlantic, and this keeps overall climate temperate, but after torrents of cold fresh water stopped this process, average annual temperatures dropped as much as 15 degrees F in less than a decade, precipitating severe stadial conditions that lasted for hundreds or even thousands of years. These meltwater pulses are known as Heinrich events, named after the scientist who first recognized this cycle.

During Ice Ages warm stages of climate cyclically caused glacier dams to burst, releasing massive amounts of cold fresh water plus icebergs.  This shut down the North Atlantic Gulf Stream which brings tropically heated water north, resulting in a sudden decline in average annual temperatures.

A graph showing average annual temperature fluctuations over the last 100,000 years from data gleaned inside Greenland ice cores.  Cyclical Heinrich Events caused the sudden declines in temperatures.

I assumed Heinrich Events severely disrupted marine ecosystems, causing decisive population declines in most fish and other ocean fauna, though a few species may have benefitted from reduced competition or other factors.  But I thought there would be no paleontological evidence because preservation and detection of animal remains during brief time intervals in marine environments seemed unlikely.  However, a recent paper highlights evidence that Heinrich Events were detrimental to marine life.  Scientists found this evidence in a seaside Sicilian cave named la Grotta Dell’Uzzo.  This cave had previously revealed the Pleistocene remains of mammoth, rhino, lion, red deer, and wild boar.  Humans have also periodically occupied this cave from the late Pleistocene through the Holocene, and scientists have excavated human skeletons, artifacts, and food remains.  Chemical analysis of human bones found in the cave helped scientists determine the diet of the hunter-gatherers who occupied the cave during the early Holocene.  They ate red deer, wild boar, shellfish, fish caught near shore (such as grouper), acorns, grapes, and wild beans and peas.  However, 1 human specimen and 1 red fox bone, dating to 8200 BP, revealed an interesting difference. Both the human and the fox ate unusual quantities of whale meat during their lifetimes.  Red foxes don’t normally include whale meat in their diet, and humans from other generations of cave dwellers here hardly ever exploited this resource. Moreover, whale bones with butcher marks on them were found associated with the human and fox specimens in the same strata.  The scientists who examined this evidence determined humans exploited climate-driven whale strandings at this locality.

Mass stranding of pilot whales in Australia.  Heinrich Events disrupted marine ecology and caused high annual mortality among many species of whales.

File:De- San Vito lo Capo, Zingaro-NatSchGeb, Uzzo-Grotte.jpg

Evidence of early Holocene mass whale strandings was discovered in this seaside cave in Sicily, known as la grotto dell’Uzzo.

The last major Heinrich Event occurred 8200 years ago, following the final dissolution of glacial Lake Agassiz in Canada.  This massive meltwater pulse disrupted fish migrations and reduced fish populations, making it harder for many species of whales to find prey.  Stressed and malnourished whales are more likely to strand on beaches.  The Gulf of Castallammare, adjacent to la Grotto Dell’Uzzo, is an acoustic dead zone difficult for whales to navigate.  This is where frequent, probably annual, whale strandings occurred for centuries, and the evidence suggests humans and foxes exploited this resource.  Based on the zooarchaeological record, the most common species of whales stranded here were pilot whales (Globicephala melus), Risso’s dolphin ( Grampus griseus ), and short-beaked common dolphin ( Delphinus dolphio ). Frequent whale strandings likely occurred worldwide following Heinrich Events.  Off the coast of North America dire wolves, bears, and other large carnivores scavenged this wealth of protein during the Pleistocene.  There were certain spots, such as the 1 in Sicily, where carnivores learned to regularly search for this bounty.  Carnivore populations may have been higher near the coast due to this additional resource.  Unfortunately, evidence of these sites were long ago inundated by rising sea level.

Reference:

http://www.nature.com/articles/srep16288

Marcello, Mannino; at. al.

“Climate-driven Environmental Changes around 8200 Years Ago Favored Incidences of Cetacean Strandings and Mediterranean Hunter-Gatherers Exploited Them” 

Scientific Reports 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 Paleo-Apalachicola River

June 11, 2016

The transition from the Ice Age to the much warmer climate phase that ended it about 15,000 years ago caused a dramatic change in the river systems of southeastern North America.  Average annual temperatures suddenly approached those of the present day, and the glaciers that covered Canada began to melt, resulting in the creation of massive glacial lakes along with a rapid rise in sea level.  More water could now evaporate and enter the atmosphere.  Storm events exceeded what present day inhabitants of earth experience today.  During the Ice Age the water table fell and smaller rivers and creeks disappeared from the surface, while larger rivers suffered a lesser discharge and were clogged with sandbars.  But when precipitation increased decisively as the glaciers melted, larger rivers swelled and began to meander, and for awhile they meandered to a greater degree than they do today.  Geologists refer to these as supermeanders.  Smaller rivers and creeks reached the surface again after the water table rose.

Apalachicola watershed.png

The Apalachicola River drains the Chipola, Chattahoochee, and Flint Rivers.  It was longer and had a larger discharge during the late Pleistocene.

In my blog article last week, I mistakenly stated the Aucilla River in Florida didn’t exist until 7,000 years ago, but when I read the scientific literature in preparation for this article, I learned that I was off by about 6,000 years.  (I’ve since edited the correction.)  The Aucilla River likely existed as a subterranean stream throughout the Ice Age, and it was probably the source for the springs that fed the ponds I discussed last week.  It emerged above ground probably about 13,000 years ago.  By 11,000 BP the paleo-Aucilla River had a greater discharge than it does today.

I wonder if this change was perceptible to the Paleo-Indians who frequented the spring-fed ponds that occurred along the present day course of the Aucilla River.  Some time between ~14,000 BP-~13,000 BP increased rainfall enlarged the ponds to the point that a river began flowing between them.  This might have occurred within the lifetime of a long-lived Indian.

The Apalachicola River is much larger than the Aucilla River, and it too had a greater discharge immediately following the end of the Ice Age.  During the late Pleistocene sea level was still much lower than it is today, and the Apalachicola River flowed over the continental shelf for 50-100 miles–territory that is now the Gulf of Mexico but was dry land then.  Seismic evidence suggests 1 of the now submerged river channels of the Apalachicola was 300 yards wide and 60 feet deep.  The phase of rivers with supermeanders and higher discharges lasted for about 5,000 years before they stabilized to modern day conditions.

Side scan sonar image of a submerged river valleys off the coast of Nova Scotia.  I couldn’t find a sonar image of the paleochannels off the Florida coast on google images.

The Chattahoochee, Chipola, and Flint Rivers join to form the Apalachicola River.  They meet near the border between southwestern Georgia and Florida.  During the Miocene over 5 million years ago this was the site of an enormous bay known as the Apalachicola embayment.  Imagine a bay where 3 major rivers emptied their contents.  Eventually, sea level fell and these rivers met and formed the Apalachicola River.

An aerial photo of the Apalachicola River as it meanders toward the Gulf of Mexico.  The paleo-Apalachicola River was probably clear, not muddy, for most of its existence.  Anthropogenic erosion has ruined the pellucid quality of the river.

Reference:

Donoghue, J.F.

“Late Quaternary Coastal and Inner Shelf Stratigraphy, Apalachicola Delta Region, Florida”

Sedimentary Geology 80 1992

Extensive Late Pleistocene to Mid-Holocene Wetlands along the Tennessee River

June 15, 2015

A paper about extinct giant beaver (Casteroides sp.) fossil remains in the mid south briefly mentions evidence for the existence of “extensive floodplain lakes and marshes along the middle stretch of the Tennessee River” during the late Pleistocene-mid Holocene.  This intrigues me. Following the end of the Ice Age, increased precipitation in the atmosphere from melting glaciers caused southeastern rivers to meander more than they do today.  Geologists actually refer to these river patterns as supermeanders, and supermeandering rivers were common between ~15,000 BP-~6,000 BP.  Meanders often get cut off from the main river channel, and they become oxbow lakes, a name that describes their curved shape.  Sediment eventually fills oxbow lakes, and during this process they become marshy.  Large oxbow lakes created by this period of supermeanders attracted huge flocks of wintering waterfowl.  Archaeologists found enormous quantities of mallard duck (Anas platyrhyncos) remains dating to the late Pleistocene-early Holocene in Dust Cave and Smith-Bottom Cave, both located in northwestern Alabama.  The ducks were brought inside the caves by early archaic Indians who enjoyed a steady diet of duck during the winter.  70% of the faunal remains in Dust Cave were birds, mostly waterfowl but also including passenger pigeon, bobwhite quail, and prairie chicken.

Diagram showing how oxbow lakes are formed.  There must have been huge oxbow lakes along the Tennessee River during the supermeandering phase of ~15,000 BP-~6,000 BP

Map of Tennessee River.  Abundant remains of ducks and other waterfowl in caves near the river suggest a very extensive wetland occurred along the middle stretch of the river during the Late Pleistocene-to mid Holocene.

Location in Lauderdale County and the state of Alabama

Caves are located  on both sides of the Tennessee River in northwestern Alabama.  They preserve evidence that early Indians ate a lot of duck.

Mallard ducks

Huge flocks of mallard ducks wintered on oxbow lakes and marshes along the Tennessee River during the late Pleistocene-mid Holocene.

Dust Cave was buried by sediment until ~15,000 BP when the nearby Tennessee River changed coarse and eroded through this sediment, exposing the cave entrance.  Indians occupied the cave from ~12,500 BP-5000 BP.  Archaeological evidence shows 5 succeeding cultures utilized the cave. The Indians buried their dead in Dust Cave and left plenty of archaeological evidence such as arrowheads and the impressions of textile weaving on clay.  Toward the end of this time, Indians utilized waterfowl less than their predecessors had and relied more on upland game.  This suggests wetlands and lakes in the region eventually were diminished in extent.

During the time of supermeanders swamp rabbits (Sylvilagus aquaticus) were common.  Flooding helped establish extensive stands of impenetrable bamboo cane (Arundinaria gigantea) known as canebrakes, a favored habitat of swamp rabbits.   Floods killed trees and deposited rich soil.  Bamboo cane thrives on open sunlit ground with well fertilized soil.

Swamp rabbits were abundant here as well.

The deepest lakes offered habitat for the freshwater drum (Aplodonitis grunniens).  This species prefers clear water with sandy or gravel bottoms.  They feed on mussels, insect larva, and small fish.  Freshwater drums, suckerfish, and catfish made up 8% of the faunal remains in Dust Cave.  Fish was an important summer food for Archaic Indians after ducks migrated north.

Freshwaterdrum.png

Indians ate freshwater drum.

The extinct giant beaver occupied the oxbow lakes and marshes created by the supermeandering patterns of the Tennessee River until Indians hunted them to extinction.  (A safe assumption, though no direct evidence of humans hunting giant beavers has ever been found.)  Perhaps, they even persisted here early in the Holocene because the habitat they favored was so extensive.  Remains of giant beavers have been found at 3 sites along the Tennessee River including Ruby Falls, Bell Cave, and ACb-3 Cave.  The latter 2 sites are located in Colbert County, Alabama.  There were at least 2 species of giant beaver–Casteroides ohioensis and Casteroides dilophidusC. ohioensis lived in the Midwest; C. dilophidus lived in Florida and south Georgia.  Scientists aren’t sure which species lived along the Tennessee River because not enough skeletal material was found to distinguish between species.  Giant beavers preferred the same habitat as the modern day muskrat (Onadatra zibethicus) and did not require wooded environments like extant modern beavers (Castor canadensis).

Photo: Giant Beaver, Castoroides ohioensis.

Giant beavers (Casteroides sp.) lived in these wetlands until the Indians overhunted them to extinction.

References:

Parmalee, Paul; and Russell Graham

“Additional Records of the Giant Beaver, Casteroides, from the Mid South: Alabama, Tennessee, and South Carolina”

Tributes to the Career of Clayton Ray, Smithsonian Series of Publications 2002

Pritchard, Erin

TVA Archaeology: 75 Years of Prehistoric Site Records

University of Tennessee Press

 

 

Rapid Sea Level Rise on the Georgia Coast

May 19, 2015

Glaciers expanded and sea levels fell during Ice Ages.  20,000 years ago, the Georgia coast was located 90 miles to the east of the present day shoreline.  The continental shelf off the Georgia coast (known as the Georgia bight) was above sea level between 80,000 BP-7,000 BP.  Near the end of the Ice Age, glacial ice melted and sea level rose rapidly but in stages.  The partial dissolution of glacial Lake Agassiz in Canada 12,900 years ago caused a sudden rise in sea level.  The Atlantic Ocean likely advanced toward the present day shoreline many miles in a few short years.  But an ice dam reformed, containing the rest of Lake Agassiz’s water until 8200 BP when it completely collapsed, releasing the rest of this great lake’s water.  (Lake Agassiz contained more water than all of the modern Great Lakes combined.)  This caused another sudden rise in sea level along the Georgia coast.  By 4500 BP the Georgia coast consisted of just 2 barrier islands separated by the southeasterly flowing Altamaha River.  The Ogeechee, Satilla, and St. Mary’s Rivers were tributaries of the Altamaha and didn’t directly drain into the Atlantic Ocean as they do today.  The Altamaha drained into a huge sound located to the east of where Little Cumberland Island stands today.  Sea level rose again, flooding and eroding the areas where the Ogeechee, Satilla, and St. Mary’s flowed into the Altamaha and splitting the 2 barrier islands into 10 smaller ones.  All of these rivers formerly flowed southeasterly, but the high marine transgression caused them to straighten to a more easterly direction.

trail map

Map of the  modern day Georgia coast.  About 4500 years ago, there were only 2 barrier islands between the Savannah River and the Florida border, and they were bisected by the Altamaha River which then emptied into a huge sound located at the same latitude as modern day Little Cumberland Island.  The other rivers in this region that today flow into the ocean were tributaries of the Altamaha.

Aerial view of Georgia salt marsh.

Aerial view of salt marsh in Glynn County, Georgia.  There are 4500 year old logs from a rapidly flooded forest underneath the surface.

Wood storks (Mycteria Americana) on a salt marsh behind Sapelo Island.  There are now 10 major barrier islands off the Georgia coast, but before 4500 years ago, there were just 2, separated by the Altamaha River.  A person using an excavator to dig here would probably find 4500-2000 year old logs in less than an hour.

The Holocene Climatic Optimum between 9000 BP-5000 BP was a warm climatic phase, especially at higher latitudes, resulting from both the northern hemispheric tilt of 24 degrees and the timing of the perihelion.  The earth was closest to the sun during the boreal summer.  Summers were much warmer but winters were cooler.  The effects of the Holocene Climatic Optimum were felt in different regions at different times.  The sea level rise on the Georgia coast occurred toward the end of this climatic phase.  The ocean’s response to the Holocene Climatic Optimum may be a factor explaining this marine transgression.  Tectonic processes (the shifting of the earth’s crust) and isostatic adjustment (the rebound and subsidence of the earth’s crust in response to the weight of glaciers) also probably played a role in this sea level rise.

Scientists studying the rapid rise of sea level on the Georgia coast find fossil trees beneath salt marshes, and they date to between 4400 BP-2000 BP.  St. Simon’s and Jekyll Islands were connected until 2000 BP.  The youngest fossil trees are found here.  This was one of the last areas of the coast to get inundated, though Ossabaw Sound was breached about the same time. There are abandoned river channels beneath salt marshes as well. Sea level is still rising but not at an unprecedented rate as global warming alarmists and political pundits claim.  Sea levels haven’t even reached the marine transgression high stand of the last interglacial known as the Sangamonian (~132,000 BP-~118,000 BP).

References:

Chowns, Timothy

“Drainage Changes at Ossabaw, St. Catherine’s, and Sapelo Islands and their Influence on Island Morphology and Spit building on St. Catherine’s Island”

American Museum of Natural History Anthropology Papers 94

Chowns, Timothy; and S. Hannah Hill

“Mid-Holocene Sea Level Rise on the Georgia Coast”

Georgia Journal of Science Abstracts 2014

Glaciers Shaped the Ohio River

May 15, 2015

Weak Ice Ages began occurring as early as 5 million years ago.  Gradually, they became more severe.  1.4 million years ago, for the first time, glaciers advanced through valleys incised by the Erigan River drainage.  This river system flowed through the present day sites of the Great Lakes which didn’t exist yet.  The Laurentide ice sheet obliterated the Erigan River system and advanced beyond another major, now extinct, river–the Teays.  The Teays River began in the North Carolina mountains and flowed in a northwesterly direction through what today is Virginia, West Virginia, Ohio, Indiana, and Illinois before emptying into the Mississippi River.  Glaciers formed a dam, blocking the northwesterly flow of the Teays River and creating the massive Lake Tight, a 7000 square mile body of water as deep as 800 feet in some spots.   Lake Tight must have been quite a sight–gray gravel and ice on the northwestern side and green boreal forests of spruce, pine, and northern hardwoods on the southeastern shore.  Many species of fish lived in the water, attracting great flocks of gulls; and it was a summer destination for duck, goose, and swan.  The churning waters spawned big waves like those of an ocean rather than a lake.  Overflow from the lake was captured by a minor tributary of the Cumberland River.  The ice forced the water to erode backward into bedrock, lengthening this tributary. This large creek/small river became the mighty Ohio river.  When the glacier retreated, the ice dam melted, releasing an incredible quantity of water into the Ohio river and incising a deeper valley toward its outlet, the Mississippi River.

The ancient Teays River was  a major regional drainage system during the Pliocene and early Pleistocene.  The advance of glaciers during Pleistocene Ice Ages dammed this river, allowing a minor tributary of the Cumberland River to capture the stream flow.  This small river became the mighty Ohio.

Map of Ohio River drainage. Glaciers pushed the water content of the Teays River south, creating the Ohio River instead.  Formerly, it was a small tributary.

Subsequent glacial advances during Ice Ages over the past 1.4 million years have had a major influence on the shape of the Ohio River.  The southern lobe of the Laurentide ice sheet frequently advanced far enough south to push sediment into the northern part of the Ohio River, damming tributaries and creating an extensive network of lakes.  During glacial maximums there were always a chain of lakes along the Ohio border with West Virginia and Kentucky.  The Illinois Ice Age was 1 of the most severe.  It lasted from ~240,000 BP-~135,000 BP.  The Laurentide ice sheet advanced as far south as northern Kentucky–its greatest extent ever.  This backed up lakes from the present day site of Louisville to the Pennsylvania border, forcing water into the Ohio River headwaters and incising 45 feet of bedrock.

Though the Wisconsin Ice Age (~114,000 BP-~11,000 BP) was not as severe as the previous glacial advance, the Ohio River valley was frequently incised by pulses of glacial meltwater.  A recent study of river sediment found that changes in the Ohio River were closely correlated with global climate change.  Warmer climate phases within the Ice Age were associated with greater incising and erosion, resulting from melting ice and large water discharge.  Colder climate phases and lower water discharge caused greater sediment build-up, known as aggradation.

Today, the Teays River valley is mostly hidden by sediment, but its descendent is clearly visible on maps.  Government officials used the Ohio River as a convenient demarcation to draw up borders between states.  Imagine how different a modern day map of the United States would look, if there had been no Ice Ages, and accordingly, no Ohio River worth noting.

Reference:

Counts, Ronald; et. al.

“Late Quaternary Chronostratigraphic Framework of Terraces and Alluvium along the lower Ohio River, Southwestern Indiana, and Western Kentucky”

Quaternary Science Reviews February 2015

 

The Destruction of a Beautiful Kettle Lake led to the Origin of JP Morgan-Chase Bank

November 13, 2014

Kettle lakes are common geological formations found in North America in any region once covered by a glacier.  When glaciers recede they often leave large chunks of ice behind.  Both wind and water borne sediment covers these blocks of ice, temporarily insulating them, but eventually the ice melts and forms a lake.

Diagram showing how a kettle lake forms.

20,000 years ago, the edge of a mighty glacier advanced as far as what today is Manhattan Island, New York.  A narrow strip of unglaciated land, about 50 miles wide, existed on the continental shelf between Manhattan and the Atlantic Ocean.  After the glacier receded it left a kettle lake behind on the southern end of Manhattan.  The lake held clear glacial meltwater and was continuously fed by underground springs.  It was 70 feet deep–evidence the block of ice left behind had been quite large.  For thousands of years, Indians used this lake as a source of freshwater because the rivers surrounding Manhattan are tidal in nature and too salty to be potable.  An Indian settlement existed on the southwestern edge of the lake in 1604 when the Dutch first established a colony on Manhattan.  The Dutch called the lake “Koelch,” meaning small body of water, but when the English took over the island, the word was mispronounced, and thereafter was called “Collect Pond.” A steep 110 foot tall hill, known as Bayard’s Mount, occurred on the north side of Collect Pond, and another steep hill, Kalch Hoek, bordered the west side.  A freshwater marsh existed to the south of Collect Pond, and 2 creeks served as outlets for the kettle lake’s overflow.  Lispenard Creek drained into the Hudson River and Old Wreck Brook drained into the East River.  Fish likely colonized Collect Pond through these creeks.  Species of fish recorded to have lived in Collect Pond included pumpkinseed sunfish, redfin pickerel, eel, and killifish. Collect Pond was a beautiful and valuable natural resource.  It provided fresh drinking water for all of Manahattan for almost 200 years, as well as winter ice skating, and summer recreational fishing.  Man then turned this heaven into hell.

File:Collect Pond-Bayard Mount-NYC.jpg

A portrait of Collect Pond painted in 1798 by Archibald Robertson.  The weeping willow is not a native species and must have been planted early in the century.  After  poison from a tannery polluted the pond, developers filled it in with dirt from the hill (Bayard’s Mount) in the foreground.  That hill also no longer exists.

Circa 1800, the stupid greedy owner of a tannery factory was responsible for dumping tannins into Collect Pond, poisoning New York City’s drinking water.  Because Collect Pond no longer provided drinkable water, city leaders decided just to fill in the lake with dirt from the beautiful surrounding hills, thus destroying this once pristine site forever.  They called this leveled land “Paradise Square,” but within decades it transmogrified into the infamous 5 Points neighborhood depicted in the violent movie Gangs of New York.  To make matters worse, organic plant material from the fill material rotted away, causing parts of the neighborhood to sink.  It was a muddy, disease-ridden slum.  Anybody with any money at all moved away, leaving the neighborhood populated by poor Irish immigrants and freed African-Americans.  Circa 1900, city leaders condemned the neighborhood and replaced it with the city municipal building where justice and injustice are still dispensed by the court.  (Other buildings and parking lots occupy the rest of the space.)

The Manhattan Municipal Building towers 25 stories high, with an additional 15 stories on the center spire. (Amal Chen/The Epoch Times)

The New York City Municipal Building now stands where Collect Pond used to be. 

 

 Aaron Burr was the Vice-President of the United States between 1800-1804.  In 1808 he responded to the ecological disaster of Collect Pond by founding the Manhattan Water Company.  His stated goal was to bring water from upstream to downtown, but instead he used the assets to start JP Morgan Bank.  The city eventually built an aqueduct to bring water from a source off the island.  Aaron Burr is best known for his duel with Alexander Hamilton.  Burr fatally wounded Hamilton in 1804.  Hamilton was the Secretary of the Treasury and a member of Thomas Jefferson’s cabinet.  Fighting duels was a childish custom.  Imagine if Joseph Biden challenged Hillary Clinton to a duel.  JP Morgan is still run by childish crooks, but at least they don’t fight duels.

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Portrait of the duel between Aaron Burr and Alexander Hamilton in 1804 drawn by J. Mund.  Aaron Burr founded JP Morgan for the purpose of funding a project to supply fresh water to New York City after Collect Pond was poisoned.  This portrait is not accurate.  The seconds had their backs turned so they wouldn’t have to testify in court as witnesses.

Reference:

Sanderson, Eric

Mannahatta: A Natural History of New York City

ABRAMS 2009

Stream Capture Events and the Range of the Robust Redhorse Sucker Fish (Moxostoma robustum)

October 8, 2014

Edward Cope first described the robust redhorse sucker fish in 1870, but it was not rediscovered until 1980, and the newly discovered populations in the Savannah and Pee Dee Rivers were not correctly identified until 1991.  It’s a rare fish listed as endangered by the state of Georgia.  Populations of this species are known from the Savannah, Oconee, and Ocmulgee Rivers in Georgia, and the Pee Dee River in North and South Carolina.  Researchers are in the process of introducing the fish to the Santee River, South Carolina where it is thought to have become extirpated.  The robust redhorse sucker fish lives in rocky pools and the slow runs of small rivers.  It spawns in shallow water with gravel bottoms.  Such environments are now far less common than in days of old because sediment from cleared agricultural and suburban development covers the gravel bottoms, making them unsuitable for spawning sucker fish.  This species spawns in late spring and early summer.  It feeds on freshwater mussels and insects, and the most common species in its present day diet is the invasive Asian clam.  The fish crushes the shells with teeth located in its throat. It grows to over 2 feet long and up to 18 pounds, and it can live for up to 25 years.

Robust Redhorse drawn by Joe Tomelleri

Robust redhorse sucker fish drawn by J. Tomalleri.

There are at least 10 species of redhorse sucker fish in Georgia including the silver redhorse (Moxostoma anisurum), river redhorse (M. carratum), notched redhorse (M. collapsom), black redhorse (M. duquesne), golden redhorse (M. erithrurum), harelip redhorse (M. lacerum), greater jumprock (M. lachner), blactailed redhorse (M. poecilurum), and striped redhorse (M. rupicates).    There may be an additional 3 species not yet given scientific names.  Sucker fish are often labeled as trash fish, but some people know better.  Fish fries featuring sucker fish are held in various locales, and the people who eat them seem to enjoy the fish.  I’ve never had the opportunity to try sucker fish.

The study of redhorse sucker genetics referenced below determined the population of  M. robustum found in the Pee Dee River diverged from the Savannah River population 1.5 million years ago.  There is a considerable distance between these 2 river drainages.  This fact inspires the obvious question: How did this species come to occupy such disparate ranges?  There is a simple explanation.  River drainages are separated by high ridges of land.  Streams that flow into major rivers often erode backwards into the ridges and occasionally erode into the stream of another river system.  These backward flowing streams then capture the other stream, causing it to reverse and flow into the other river drainage.  This is how fish species spread into different river drainages.  The Savannah River drainage is too far away from the Pee Dee River to have ever shared a stream capture event.  However, the robust redhorse sucker fish formerly occurred in the river drainage between these 2 distant river systems.  The Santee River drainage served as a conduit between the 2.  Various stream capture events between the Savannah and Santee and between the Santee and Pee Dee facilitated the exchange of many species of fish.

South Carolina Lakes and Rivers Map

Map of South Carolina river systems.  A series of stream capture events in the Southern Appalachians likely led to the colonization of the robust redhorse sucker fish and many other species of fish into adjacent river systems.  Populations of this species have been found in the Savannah river system and the Pee Dee river system.  Note the considerable distance.  The intervening population has become extinct.

Effects of stream capture on species-richness of adjacent drainage basins based on dispersal, vicariance, and extinction

Figure showing how stream capture events can occur and result in the spread of a fish species into another river system.

Streams erode backwards more rapidly in overgrazed landscapes.  Pleistocene megafauna overgrazed many areas, thus increasing the frequency of stream capture events in the past.

References:

Darden, T.L.; and C.M. Tarpey

“Genetic Characteristics of the Savannah and Pee Dee River Populations of Robust Redhorse (Moxostoma robustum) with Conservation Implications”

Copeia 2014

Matthews, William

Patterns in Freshwater Fish Ecology

Springer 1998