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39-459: Repeated growth and retreat of the North American glacial sheet resulted in fluctuations of sea level over several thousand years. Florida submerged and emerged several times leaving behind established terraces assigned by mineral deposits and maximum sea level relative to the current mean sea level . These marine terraces and shorelines were named by various geologists, verified and mapped by

78-409: A lower portion of the moraine. Multiple outlets could form through low spots too until one would become dominant after erosion lowered both the outlet and lake surface. Ice melt and rainfall carried large quantities of clay , sand , and gravel from the ice mass. Clays could be moved long distances by moving water, while sand and gravel could not. Thus, sand and gravel landforms developed along

117-644: A suture zone between the Laurentide and Cordilleran ice sheets formed the Cypress Hills , North America's northernmost point that remained south of the continental ice sheets. During much of the glaciation, sea level was low enough to permit land animals, including humans , to occupy Beringia (the Bering Land Bridge ) and move between North America and Siberia . As the glaciers retreated, glacial lakes were breached in great glacial lake outburst floods such as

156-468: A whole. The striations made by the ice field in moving over the bedrock show that it moved principally to the west through the passes of the coast range. Whenever the ice sheet melted from the north at a moraine , water would begin to pond in the divide between a moraine and the ice front. The ice would act as a dam as water could not drain through the ice sheet, which in the Wisconsin period covered most of

195-739: Is equivalent to Marine Isotope Substage 5e and the Eemian. In case of this usage, Marine Isotope Substages 5a, 5b, 5c, and 5d are collectively referred to as the Eowisconsinan Stage . In its broadest sense (sensu lato), the Sangamonian Stage precedes the Wisconsinan (Wisconsin) Stage and follows the Illinoian Stage in North America. Research concerning the age and degree of development of

234-589: Is the term used in North America to designate the Last Interglacial (130,000-115,000 years ago) and depending on definition, part of the early Last Glacial Period , corresponding to Marine Isotope Stage 5 (~130-80,000 years ago). While often historically considered equivalent in scope to MIS 5, it is now often used in a more narrow sense to refer to the Last Interglacial only (corresponding to MIS 5e and

273-559: Is well developed in northeastern and extreme northwestern Florida. At this time the county is mostly dry except for the southern coastline. The Cody Scarp is a shoreline of the Wicomico as well as the aforementioned Okefenokee. The Ocklochonee River empties into a large, wide estuary or inlet leading to the sea. The ground for what will be the Tallahassee Regional Airport remains underwater. The Penholoway terrace and shoreline

312-560: The Bering Strait is believed to have allowed human occupation of this area which provided potential access for some of the first humans to move between North America and Siberia in Asia (see Settlement of the Americas ). Other human migration routes also opened during interglacial periods in both Europe and Asia. North American flora and fauna species were distributed quite differently during

351-709: The Great Lakes . At the height of the Wisconsin Episode glaciation, the ice sheet covered most of Canada , the Upper Midwest , and New England , as well as parts of Idaho , Montana , and Washington . On Kelleys Island in Lake Erie , northern New Jersey and in New York City 's Central Park , the grooves left in rock by these glaciers can be easily observed. In southwestern Saskatchewan and southeastern Alberta

390-512: The Illinoian glacial topography that its glaciers extended over. The Late Wisconsin ice sheet extended more towards the west than the earlier movements. This may have been due to changes in the accumulation center of the ice sheet, topographic changes introduced by the Early phase or by pressure changes in the ice mass in the north. The Labrador Ice Sheet centered east of Hudson Bay. Expanding towards

429-565: The Kankakee Torrent , which reshaped the landscape south of modern Chicago as far as the Ohio and Mississippi Rivers. Two related movements have been termed Wisconsin: Early Wisconsin and Late Wisconsin. The Early Wisconsin was the bigger of the two and extended farther west and south. It retreated an unknown distance before halting. During this period of quiet, the glacial deposits were eroded and weathered. This first Wisconsin period erased all

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468-680: The Pinedale glaciation . The Wisconsin glaciation extended from about 75,000 to 11,000 years ago, between the Sangamonian Stage and the current interglacial, the Holocene . The maximum ice extent occurred about 25,000–21,000 years ago during the last glacial maximum , also known as the Late Wisconsin in North America. This glaciation radically altered the geography north of the Ohio River , creating

507-581: The USGS . Each glacial retreat caused sea level to rise less than the previous warming event, giving an extremely accurate depiction of the appearance of Florida. Leon County was studied in detail by C. W. Hendry and C. Sproul in 1966. The Hazelhurst terrace and shoreline (formerly the Brandywine) was assigned by C. W. Cooke and includes Vernon's Coastwise delta plain and MacNeil's high Pliocene terrace. Deposits are found between 97 and 65.5 meters (320–215 feet). During

546-592: The Waterman Hills researchers found that Juniperus osteosperma and Pinus monophylla were early to mid-Holocene dominant trees, while Monardella arizonica has been a continuously present understory plant. Celtis reticulata is an example of a plant present in the early Holocene following Wisconsin glacial retreat, a species no longer present at the Waterman Mountains site. Sangamonian The Sangamonian Stage (or Sangamon interglacial )

585-631: The Coharie is included with the Sunderland terrace in USGS mapping. One ancient island appeared in the extreme northwest portion of the county near the junction of Meridian Road and County Road 12. The second island was located in the general vicinity of U.S. 319 and Sunnyhill Road just south of the Florida/ Georgia border. The third of the northern islands of the Coharie was located in extreme northeast portion of

624-715: The Early Pleistocene glacial retreat. The Okefenokee is defined by sediments at 52 to 30.5 meters (170–100 feet) above current mean sea level. The dry land mass left behind can best be described as an oddly shaped peninsula overlaying the islands of the Coharie as well as added land that is connected to adjacent peninsulas in other counties. During the forming of the Okefenokee, the Ochlockonee River began to take shape as did rivers in other counties in Florida. The large inlet in

663-648: The European Eemian). It preceded the Wisconsinan (Wisconsin) Stage and followed the Illinoian Stage in North America . The Sangamonian Stage, originally the Sangamon interglacial stage, is defined on the basis of the Sangamon Soil, a paleosol , which is developed in contemporaneous colluvium and older glacial tills and loesses and overlain by Wisconsinan loesses or tills. Although originally described from water wells in northwestern Sangamon County, Illinois ,

702-631: The Glasford Formation, which fill an ancient and buried Mississippi River valley in north-central Illinois. The age of fluvial sediments overlying the youngest glacial till (Radnor Member) of the Glasford Formation yield optically stimulated luminescence (OSL) dates that averaged 131,000 BP. These OSL dates demonstrate that the Illinoian Stage ended and the Sangamonian Stage started about 125,000 BP. These dates refute older dates, i.e. between 220,000 and 450,000 BP, given by older publications for

741-472: The Sangamon Soil demonstrates that it actively developed, at the least, over all of Marine Isotope Stage 5, which is a period of time from 125,000 to 75,000 BP. Unlike Europe, the development of ice sheets in Canada was limited during Marine Isotope Substages 5b, 5c, and 5b and either completely disappeared or were greatly reduced in size during Marine Isotope Substage 5a. Because of the continuous development of

780-646: The Sangamonian Soil in the Midwest and the limited development of ice sheets in North America during this marine isotope stage, the Sangamonian Stage, unlike the Eemian in Europe, is regarded as encompassing all of Marine Isotope Stage 5. The start of the Sangamonian Stage is constrained by optically stimulated luminescence (OSL) dates obtained from fluvial deposits of the Pearl Formation and Illinoian glacial tills of

819-702: The Talbot is better developed in Leon as well as Bay County , Wakulla , and Walton County . USGS Terrace and shoreline map of Florida. Wisconsinian glaciation The Wisconsin glaciation , also called the Wisconsin glacial episode , was the most recent glacial period of the North American ice sheet complex, peaking more than 20,000 years ago. This advance included the Cordilleran Ice Sheet , which nucleated in

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858-476: The Wisconsin era, due to altered temperatures, surface water distribution, and in some cases coverage of earth surface by glaciers. A number of scientific studies have been conducted to determine species distribution, particularly during the Late Wisconsin and early to mid-Holocene. An example of findings is from the investigation of flora species using pollen core samples in present-day northern Arizona. Here in

897-426: The county and overlapping the county line between Leon and Jefferson County . To the south lay 3 more islands. The first was located generally north and near Elinor Klapp-Phipps Park and surrounding area. The second and largest covered the area where most of Tallahassee is today. It extended from near Interstate 10 in the north to the capitol complex in the south, to just east of State Road 263. The third island

936-854: The current type sections for the Sangamon Stage are the Rochester section in eastern Sangamon County and the Chapman section in Morgan County, Illinois . In the Rochester Section, the Sangamon Soil is developed in Sangamonian colluvial sediments, called “accretion gley”, that accumulated contemporaneously with the development of the Sangamon Soil. In the Rochester section, the Sangamon Soil is developed directly in Illinoian glacial till and overlain by Roxana Silt,

975-427: The glacier when it melts back is called the ground moraine or till plain . Till is highly permeable and creates a large ground reserve for water. This formation is highly desirable for human economic development as a source of water. Prehistoric human migration was likely greatly influenced by this last glacial period, as during much of the Wisconsin era, the formation of a land bridge known as Beringia across

1014-518: The interstadial period of late Pliocene to early Pleistocene epoch, the Hazelhurst terrace and shoreline was created in many counties east to west. Gadsden in particular had a very large land mass not only created by rising and lowering sea levels, but from depositions from the Apalachicola River on Gadsden's west side. Leon County remained completely submerged. The Coharie terrace and shoreline

1053-400: The northeastern part of the county left the land capable of supporting a more recognizable Lake Iamonia . Eastern Leon had a large inlet reaching as far as the northeastern portion of the county. The Cody Scarp is the remnant of the Okefenokee. What would become Lake Lafayette is a Pleistocene river delta with the lake's eastern section accessing the sea. The Wicomico terrace and shoreline

1092-581: The northern North American Cordillera ; the Innuitian ice sheet , which extended across the Canadian Arctic Archipelago ; the Greenland ice sheet ; and the massive Laurentide Ice Sheet , which covered the high latitudes of central and eastern North America. This advance was synchronous with global glaciation during the last glacial period, including the North American alpine glacier advance, known as

1131-495: The oldest of the two regional Wisconsinan loesses. In its typical and broadest usage, the Sangamonian Stage is equivalent to all of Marine isotope stage 5 between 75,000 and 125,000 BP. Although it includes the same time span, the Sangamonian Stage ( sensu lato ) is not temporally equivalent to the Eemian in Europe . In its much less common usage, the Sangamonian Stage ( sensu stricto )

1170-423: The proglacial river valleys. Numerous small, isolated water bodies formed between the moraine and the ice front. As the ice sheet would continue to melt and recede northward, these ponds combined into proglacial lakes . In areas without an available outlet, the water levels would either continue to rise until reaching one or more low spots along the rim of a moraine, or the ice sheet would retreat, opening access to

1209-409: The sides and front of the ice sheet; elongated accumulations of this material are known as kames . Mounds along the frontal edge of the ice are called moraines . Wherever a subglacial tunnel began infilling, long winding formations known as eskers would form. The sweeping plain of sand and gravel beyond the ice margin and a terminal moraine is called an outwash plain . The materials left under

Leon County Pleistocene coastal terraces - Misplaced Pages Continue

1248-556: The southwest, it reached into the eastern edge of Manitoba and across the Great Lakes to the Ohio River , upwards of 1,600 miles (2,600 km) from its source. Its eastern lobes covered New England and reached south to Cape Cod and Long Island, New York . The Keewatin Ice Sheet began west of Hudson Bay in the Canadian Territory of Keewatin . The ice moved south some 1,500 miles (2,400 km) into Kansas and Missouri. To

1287-506: The start of the Sangamonian Stage. The steppe bison ( Bison priscus ) migrated into the heartlands of North America from Alaska at the beginning of the Sangamonian, giving rise to the giant long-horned bison Bison latifrons (which is first known from the Snowmass site in Colorado, dating to around 120,000 years ago) and ultimately all North American bison species, and marking the beginning of

1326-536: The west, it reached 1,000 miles (1,600 km) to the foothills of the Rocky Mountains . The Cordilleran Ice Sheet has left remnants throughout the Northern Rocky Mountains . Unlike the other two ice sheets, this one is mountain based covering British Columbia and reaching into northern Washington State and Montana . The Cordilleran Ice Sheet has more of an Alpine style of many glaciers merged into

1365-607: Was applied by C. W. Cook in 1931 and was named for the Great Coharie Creek , a tributary of the Black River in North Carolina . It is associated with a Pre-Illinoian interglacial and was the third rise in sea level during the Early Pleistocene glacial retreat and left behind dry land in the form of six distinct islands. The Coharie is defined by sediments at 65 to 52 meters (215–170 feet) above current mean sea level. In Florida

1404-524: Was assigned by Cooke and is named for the Wicomico River in St. Mary's County, Maryland and Charles County, Maryland . The Wicomico is associated with the Sangamonian Stage between 75,000 and 125,000 years ago. and was the fourth rise in sea level during the Early Pleistocene glacial retreat. The Wicomico is defined by sediments located at 30.5 to 21 meters (100–70 feet) above current mean sea level. The Wicomico

1443-520: Was assigned by Cooke and named after Penholoway Creek in Wayne County, Georgia and is associated with the Sangamonian Stage. The Penholoway is defined by sediments located at 21 to 13 meters (70–42 feet) above current mean sea level. The seaward boundary is generally better defined than the landward boundary. In Leon County, the Penholoway is a reduction of the Wicomico. The Talbot terrace and shoreline

1482-515: Was assigned by Cooke and named for Talbot County, Maryland . The Talbot is associated with the Sangamonian Stage. The Talbot is defined by sediments located at 12 to 7.5 meters (42–25 feet) above current mean sea level. In Leon County the Talbot existed along the Leon/ Wakulla County line. The Talbot is not well developed in Florida as it is in Maryland and other states. However, within Florida,

1521-451: Was to the west and encompassed an area near Arvah Branch including I-10, U.S. 90, and north to Miccosukee Road. The Okefenokee terrace and shoreline was assigned by MacNeil in 1950 and named after Okefenokee Swamp . It includes deposits of the Sunderland terrace assigned by Cooke. It is associated with a Pre-Illinoian interglacial ( Yarmouthian ) and was the third rise in sea level during

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