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Sideling Hill Road Cut Sideling Hill is a SYNCLINAL RIDGE It took about 350 million years to form! When driving through the road cut… Think AFRICA! AFRICA?!!! SIDELING HILL road cut AFRICA This is hard to understand using a current world map – but what if we could go back 200 million years? 200 million years ago (Jurassic) 100 million years ago (Cretaceous) Record observations: Current 200 million years ago, Africa (Holocene) and North America were next to one another! This is an HISTORIC example of a convergent plate boundary. What has changed about the relative positions of North America and Africa over the past 200 years? What type of plate movement is this? The continental collision of North America and Africa resulted in the formation of the Appalachian Mountains and portions of the Atlas mountains. A current example of continental collision: Appalachians Atlas The Himalayas When Africa and North America collided 350 million years ago, the sedimentary rocks of our region folded! 1. Initial arrangement 2. Compression 3.After collision: of sedimentary rocks Folding animation In animation, select ductile deformation with compression. Click on action button below for a review of Rock Stress. To Rock Stress review To Move On Rock Stress = sedimentary rock layers Compression Tension When rock is subjected to stress, brittle rocks would break (faulting) and ductile rocks would bend (folding). Shear Exploring Earth example Rock Stress = sedimentary rock layers Compression Tension Assuming we are dealing with ductile rocks, draw three diagrams to hypothesize what Shear would happen to these horizontal rock strata if subjected to these types of stress. Exploring Earth example Select ductile deformation to review Rock Stress = sedimentary rock layers Compression Tension Assuming we are dealing with brittle rocks, draw three diagrams to hypothesize what Shear would happen to these horizontal rock strata if subjected to these types of stress. Exploring Earth example Select brittle deformation to review • A SYNCLINE is a U- shaped downfold. Synclines initially form valleys. (smile) • An ANTICLINE is an A-shaped upfold. Anticlines initially form ridges. (frown) What is Sideling Hill? Anticline OR Syncline? Ridge OR Valley? Does this relationship make sense? How you explain a SYNCLINAL RIDGE? Draw a diagram showing the arrangement of rock strata within Sideling Hill. Highlight the meta-anthracite coal layer (the black layer) • Your diagram should look something like this: When a syncline initially forms it is a valley with anticlines on either side. Extend the rock strata in your diagram to create two anticlines on either side of Sideling Hill. Hint: Sideling Hill will now be the lowest point of your diagram. Your diagram should look something like this: Dashed lines represent the Sideling Hill road cut Congratulations! You have just recreated the last 200 million years! Erosion of Folds Initial folding: Following erosion: • What is the view from the top of Sideling Hill? • What would the view have been like 200 million years ago? Is this the whole story? The black layer (highlighted on your diagrams) is meta-anthracite coal. • This is the eastern-most coal in the U.S. • For meta-anthracite coal to form at least 7000 feet of rock must be above this layer. • How does this information alter your diagrams of 200 million years ago?
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