I. The Ozarks region is one of the oldest and most unique geologic regions in North America

II. Three of the four main geologic eras are represented in the Ozarks

1. Paleozoic Era (800 to 225 million years ago)
   • The Ozarks was dry land when clay from seas washed upon the region and became shale as it dried
   • As the seas first covered the Ozarks and then retreated, deposits of Dolomite up to 500 feet thick were laid down
   • As the seas retreated climatic changes also took place and arid conditions arrived bringing with it sand deposits
   • The region was then once again covered by seas with thick deposits of Limestone being laid down and forming a partial ring around the Ozarks
2. Mesozoic Era (225 to 65 million years ago)
   • During this period the Ozarks were covered off and on with seas, but for only short periods of time
   • During the latter stages of this era Iron Ore was deposited in sinkholes left behind due to erosion
3. Cenozoic Era (65 million to present time)
   • There was a dramatic geologic uplift at the beginning of the this era, probably due to the imbalances in the earth's surface
   • The last major event in the geologic history of the Ozarks was three different episodes of glaciation which affected only the Northern parts of the region
4. Gradual but persistent erosion then began to take place which formed what we now know as the Ozarks Plateau

1. Karst is characterized by the following elements
   • Barren, rocky soil
   • caves, of which there are over 4000 in the Ozarks
   • sinkholes
   • underground rivers
2. Other areas of the world characterized by Karst are;
   • Southern France
   • Kwangsi area of China
   • Yucatan peninsula of Mexico
   • Balkan region
3. The development of Karst is a systematic process
   • Dense limestone deposits near the surface must be present
   • As this limestone dissolves, cracks form and water seeps into fissures thus producing a jagged and rough terrain
   • Caves and underground rivers then form as the water is trapped under the limestone layers
   • Sometimes these caves extend close enough to the surface that their tops collapse, forming sinkholes which serve as natural drainage for rivers and streams

1. Occurred on December 16, 1811
2. Located in Southeast Missouri near the town of New Madrid
3. Aftershocks and tremors lasted for months afterward
4. No recorded loss of life occurred due to the sparsely settled population
5. Greatest manifestation of the quake was the creation of Reelfoot lake in Western Tennessee which is 70 miles long, 20 miles wide and as deep as 100 feet in some areas.