ALABAMA GEOLOGY

North American can be divided into 8 distinct physiographic regions based on landscape features, which are mostly controlled by the geology of the regions.

Physiographic Hierarchy Physiographic Regions are the largest landscape divisions recognized on a continent.  They are based on rock type and age, geologic structure and history and generally parallel major geologic units.   They can be thought of as the landscape divisions that can be seen from space: plains, mountain ranges, etc.  Physiographic Provinces are components of Physiographic Regions and represent an area within a region whose pattern of relief features or landforms differs significantly from that of adjacent provinces. Physiographic Sections are components of Physiographic Provinces based on geographic distribution.   physiographic districts are components of Physiographic Sections based on local landforms

Physiographic Sections in Alabama There are five sections in Alabama: three belongs to the Appalachian Highlands region; one to the Inland Plains and one to the Coastal Plain regions.  Region: Atlantic Plain Province: Coastal Plain  Section: East Gulf Coastal Plain Region: Appalachian Highlands Province: Piedmont  Section: Piedmont Upland Province: Valley and Ridge Section: Tennessee Province: Appalachian Plateaus  Section: Cumberland Plateau Region: Interior Plains Province: Interior Low Plateaus Section: Highland Rim

Physiographic sections of Alabama.

Piedmont Districts Northern Piedmont Upland Southern Piedmont Upland

Piedmont Upland Section Deep soil horizon and saprolite,

Valley and Ridge “Tennessee Section” Image of the Valley and Ridge showing zigzag ridges in bottom right.  Birmingham is top left.

Cumberland Plateau

Highland Rim Section

East Gulf Coastal Plain

ALABAMA’S GEOLOGIC HISTORY

Cambrian (505-542 mya) Early Cambrian Late Cambrian No sedimentary rocks: Suggests land above Sea Level Late Cambrian Progressive rise in sea level Alabama lay beneath warm shallow ocean Rock Formations: Dolomite Chilhowee, Shady, Knox Group, Copper Ridge

Ordovician (438-505 mya) Taconomic Orogeny Alabama lay to the south or orogenic activity Volcanic Eruptions Covered millions of square miles, 1 to 2 meters thick Alabama covered in shallow marine. Rocks limestone: Chickamauga, Knox Group Bentonite clay: from volcanic eruption

Silurian (396-438 mya) Red Mountain Formation – Most Important Iron Ore Shale, Siltstone, Sandstone, Limestone, Hematite Shallow seas still covered area

Devonian (350-396 mya) Marine Deposits Frog mountain sandstone Chattanooga Shale

Mississippian (320-350 mya) Marine Deposits Rocks responsible for cave formation Rocks Fort Payne Chert Tuscumbia Limestone Pride Mountain Formation Hartselle Sandstone Bangor Limestone

Pennsylvanian (286-320 mya) Coal Age Tropical Forests Assemblage of Pangea Birth of Southern Appalachians “Alleghany Orogeny” Rocks Pennington, Parkwood, Pottsville Formations

Coal Cyclothem

Unconformity (286 – 144 mya missing) Missing Formations Permian, Triassic, Jurasic Possible Cause Alabama experiencing period of uplift, which lacked sedimentary deposits.

Cretacious (65-144 mya) Pangea Break-up Gulf of Mexico Forming Warm Global Climate Known for Chalk Deposits – Selma Chalk Emile Landfill 3 sets of rocks Tuscaloosa Group: Freshwater Deposits Eutaw Formation: Marine sands and muds Selma Chalk: Chalk & Marls Cocoliths & Foraminifera Wetumpka Impact

Emile Alabama

Emile Alabama

Paleogene/Neogene (65-Present) Alabama Coastal Plains

ALABAMA’S POINTS OF INTEREST

Alabama State Parks

Wetumpka Impact Crater

Wetumpka Impact Crater

Wetumpka Impact Crater

Wetumpka Impact Crater Location: East of Wetumpka When: Cretaceous, 83 MYA Size: Five mile wide crater created by object 1000 feet in diameter. Evidence: 1) Sharply bent rocks pointing toward the center of the impact and 2) Shocked quartz History 1891: State Geologist Eugene Allen Smith described area as structurally disturbed. 1972: Geological Survey of Alabama Geologist Tony Neathery noted a catastrophe had occurred, but source unknown. 1998: 2 well drilled by a research team from Auburn and Found shocked quartz. ·       

ALABAMA CAVES

Alabama Caves Desoto Caverns Manitou Cave Rickwood Caverns Russell Cave Sequoyah Caverns Cathedral Caverns

AL/MS BARRIER ISLANDS

AL/MS Barrier Islands

Dauphin Island

Dauphin Island

Land-Loss Trends

Mobile Bay

Evolution of Mobile Bay

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