CompuServe Messages

Kamron >> The deposits having slopped over the edge of the shelf would have seams that tilted upward. The general direction of the force pushing on them if it came from an ocean basin plate would be working the section in an upward angle. How would this transfer back hundreds of miles behind the coast leaving the coast in many areas relatively flat? << The original angle of the rock layers would only be a couple degrees (or less) from horizontal–we're talking about an area hundreds of miles wide, with very gentle slopes. Most of the compression would be in the horizontal direction. The flat coastal plains you see today are the result of weathering of the fold mountains, and deposition of sediments from rivers running from the mountains to the sea. The coastal plains are relatively recent features. >> Looking at the eastern US mountains…there has been a general spreading since it separated from the african coast. When did the pushing occur there to form the mountains? << The Atlantic closed (with continental collision) first, then opened, as it continues to do today. The collision occurred during Devonian time, creating the mountains of the eastern US. The Atlantic started opening up again in Triassic time. Howard