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Lecture 2 Geology – Glaciacian – Landform Regions.

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1 Lecture 2 Geology – Glaciacian – Landform Regions


3 Bedrock foundation of Ohio landform Composed of different kinds of rock Highly susceptible to erosive forces, but form basis of our soils 11 different rocks that comprise our bedrock in Ohio

4 Conglomerate Sandstone Shale Siltstone Limestone Dolomite Chert Clay Gypsum Coal Salt

5 3 categories of rocks in Ohio: Igneous – Igneous rock is formed through the cooling and solidification of magma or lava. Sedimentary – Sedimentary rock is a type of rock that is formed by sedimentation of material at the Earth's surface and within bodies of water. Metamorphic – Metamorphic rock is the transformation of an existing rock type, in a process called metamorphism, which means "change in form". How rocks form animation Images of 3 types of rock

6 All Ohio bedrock is stratified Occurs in layers Formed by sediment deposits left by ancient seas, swamps, and marsh land Forms what we call Sedimentary Rock

7 Fossil formation Plant and animal decomposition Became embedded in sediment layers – water, dry out, water, dry out… Fossils show what plants and animals lived during different time periods, as well as what the land form was like (under sea?)

8 Broken up into Era’s and Periods

9 Based on Era’s and Period’s Track geologic activity over long period of time Provide “picture” of landform conditions – again, under water, dry out…

10 All geologic time prior to Paleozoic Era 4.5 billion years ago to 544 million years ago First Invertebrates Precambrian

11 Start of Paleozoic Era Marine seas Limestone sediments Cambrian

12 Warm, shallow seas Bryozoans First land plants image of bryozoan Ordovician

13 Cleveland area covered by Silurian Sea during most of this period Return of warm, shallow seas Limestone, dolomite Halite Silurian

14 Dry early, then seas again Columbus limestone formation Ohio shale on top of limestone Devonian

15 Ohio Shale is very dominant in NE Ohio Evident in Rocky River Formed by small grains of mineral (clay / mud) Devonian

16 Period saw more sands and silts Led to formation of sandstone Black shale (Bedford shale) Berea sandstone Mississippian

17 Amherst, Ohio – home to one of the largest sandstone quarries One of the thickest layers of sandstone formation at 200’ thick

18 Again Ohio is covered by sea, but more coastal swamps Two important minerals formed during this period Sand and clay buried and compressed marsh vegetation to form coal Flint also formed during this period out of limestone–Ohio’s State Mineral Coal is Ohio’s most important mineral Pennsylvanian

19 Said to be last period for Ohio rock formation Sea covered but more coastal plain swamp However… Permian

20 No rock formation? No fossils Why? – different theories Geologists theorize that rock formed but was likely removed by erosion Mesozoic & Cenozoic Eras

21 Geologic Map & Cross Section of Ohio showing closest rock to surface:

22 Now what?

23 Glaciacian

24 4 classical known glacial periods Nebraskan Kansan Illinoian Wisconsinan

25 56 of Ohio’s 88 Counties at one point were covered in ice 1,000 to 8,000 feet thick Over a period of million’s of years Continental glacier images

26 Last glacial activity was about 25,400 years ago Wisconsinan End moraine Ground moraine & esker

27 Estimated to be 8,000 feet thick over Cleveland End moraines – Geologists measure ice movement by studying till left as glacier receded Plants & Animals – Impacted by ice & temperature, moved from needle bearing trees (spruce-fir-pine) to current broad leaf species (oak-maple-beech). Animals better adapted, demise more related to over hunting.

28 Picture Ohio flat from layers of build-up from ancient seas 60 million years of erosion – stream flows, wind, freeze & thaw – then eroded surface into rolling hills, steep hills similar to SE Ohio Last ice age came through and shaped current landscape - Polished rock surfaces, glacial grooves

29 Kames & Eskers – deposits left by glaciers forming various landscape features Valleys – may appear like valley formed by glacier movement, but some are glacial till Cuyahoga – 500’ old valley under river Till = glacier dirt

30 Are we done? Geologists predict that we could se another Ice Age that could possibly include Ohio Not in our lifetime, but what happened to Global Warming?

31 Now what?

32 Landform Regions

33 Nevin Fenneman – U of C Geology Professor Described 5 Physiographic Regions that exist in Ohio Regions: Lake Plains Till Plains Bluegrass Unglaciated Appalacian Plateau Glaciated Appalacian Plateau


35 Lake Plains – Primarily NW Ohio but runs along entire shoreline Includes Cleveland Very flat, fertile but poorly drained soils Great Black Swamp Areas of sand dunes / bars Number of roads built on the ridges. Lake Plains

36 Till Plains – Western part of the State Less flat, better drainage Rich farmland Hills composed of boulders and soil left from glaciers Southwest of Cincinnati- Clay soils are hard and poorly drained “Crawfish Land” due to conditions ripe for crawfish burrows. Crawfish (or crayfish) image Crawfish chimney Till Plains

37 Bluegrass – Small area in Southern Ohio Famous area for Serpent Mound, known for a possible meteor explosion and well known Indian burial place Serpent mound Bluegrass or Lexington Plain

38 Unglaciated Appalachian Plateau – Southeast portion of the State Primarily sandstone outcrop Area of fertile soils Undisturbed vegetation (at least from glaciers) Unglaciated Appalachian Plateau

39 Glaciated Appalachian Plateau – Just South of Cleveland Less hilly More fertile agricultural area then the unglaciated region. Glaciated Appalachian Plateau

40 Ohio blessed with abundant fresh water – drains to Lake Erie to the North and Ohio River to the South Over 6,000 streams in 18 watersheds Third of water lost to evapotranspiration, third to runoff, and third that eventually infiltrates and re-charges groundwater Western Ohio stores more due to limestone & permeable glacial outwash storage River drainage and watersheds

41 Watershed Land area drainage Rain & snow melt “Bowl”

42 In 1970, Ohio ranked 5 th in the nation in water use – consumption by residents, industry, & agriculture Productive drilling (ground H2O), but need to be aware of valuable resource

43 Rocky River Nature Center Field Trip – Focus on Geology / Some Glacial Impacts Meet at 1:00 pm @ Nature Center

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