CompuServe Messages

Doug, Mr. Dalziel may well have the right of it. I don't know. I only know that my text describes exotic terranes that don't clearly match either Laurentia or Baltica as being involved in the Taconic orogeny. >> In the next late-Devonian map they are more firmly connected and the southeastern U.S. is scraping along Peru – this is the event they associated with the Acadian orogeny, thus I guess Laurentia is getting << This is a bit surprising. My text says that Gondwanaland was assembled from continents and microcontinents very early in the Paleozoic, or even in the late Proterozoic, and stayed pretty well in one piece until it broke up in the mid-Mesozoic. I'd be very interested in learning how the SE US could "scrape along" Peru, on Gondwanaland's _west_ coast, then swing north around the northern coast of Gondwanaland in time to suture to Baltica in the late Devonian or early Pennsylvanian. >> If all of the fold mountains from the pre-Pangaean continental collisions wore away, we have been barking up the wrong tree in trying to explain the Appalachians in such terms. Were they completely worn away all up and down the east coast, or did significant parts survive? << As I understand it, the original Taconic, Acadian, and Alleghenian mountain ranges are all long gone from erosion. What we see today as the Appalachian Mountains are the long-buried roots of those mountains, which were recently uplifted enough for erosion to strip away the overlying Mesozoic sediments and expose the ancient folds and faults. Jon W.