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In Arkansas, the aluminum hydroxides in bauxite form small oolites and pea-sized pisolites and outcrop or are located very close to the surface under thin sediments. The resource was first mined in 1898, 11 years after the State Geologist, John Branner, identified it in a sample from Pulaski County, Arkansas .
Three major ice centers formed in North America: the Labrador, Keewatin, and Cordilleran. The Cordilleran covered the region from the Pacific Ocean to the eastern front of the Rocky Mountains and the Labrador and Keewatin fields are referred to as the Laurentide Ice Sheet. Central North America has evidence of the numerous lobes and sublobes.
Rock glaciers are normally found at high latitudes and/or elevations, and may extend outward and downslope from talus cones, glaciers or terminal moraines of glaciers. [1] There are two types of rock glaciers: periglacial glaciers (or talus-derived glaciers), and glacial rock glaciers, such as the Timpanogos Glacier in Utah, which are often ...
Physical and human geographic features of Arkansas. The geography of Arkansas varies widely. The state is covered by mountains, river valleys, forests, lakes, and bayous in addition to the cities of Arkansas. Hot Springs National Park features bubbling springs of hot water, formerly sought across the country for their healing properties.
The Geological Survey of Arkansas was first established in 1857, at the direction of Governor Elias Nelson Conway. David Dale Owen was the agencies first geologist. Initially, the agency received funding for only three years, which limited the agencies findings and publications, and the agency was left without funding during the Civil War.
Beginning around 11,700 B.C.E., the first indigenous people inhabited the area now known as Arkansas after crossing today's Bering Strait, formerly Beringia. [3] The first people in modern-day Arkansas likely hunted woolly mammoths by running them off cliffs or using Clovis points, and began to fish as major rivers began to thaw towards the end of the last great ice age. [4]
A minor series of glaciations occurred from 460 to 430 Ma, and there were extensive glaciations from 350 to 289 Ma. The Late Cenozoic Ice Age has seen extensive ice sheets in Antarctica for the last 34 Ma. During the last 3 Ma, ice sheets have also developed on the northern hemisphere.
Latitudinal gradients were so sharp that permafrost did not reach far south of the ice sheets except at high elevations. Glaciers forced the early human populations who had originally migrated from northeast Siberia into refugia, reshaping their genetic variation by mutation and drift.