CompuServe Messages

>> I asked the ranger where the material that piled up in layers came from? He said that it blew in.>> The "flat" layers exposed in the Grand Canyon that form the most spectacular colors and rock formations are sandstones, limestones, and other types of rocks. Some of the layers may be ancient dune fields or sand fiels, but I'm not sure of that. Others represent ancient sea-beds, etc. The most ancient layers are schists (if I recall correctly, originally sedimentary rock) and are very ancient. The reddish layers that are above these schists lie unconformably on top of them, indicating that erosion occurred before the formation the other layers. << Where did the layers come from?>> Thus, the layers come from a variety of sources, depending on what layer you are talking about. If that is all the ranger said — that "they blew in"– then they need a new ranger out there! << The layers came from the Sun.>> Since the sun is not made of silica or carbonates, which probably constitute most of the material you see when you look at the walls of the Grand Canyon, this is highly unlikely. << The geologic table from the beginning of time up until the top of the Cretaceous is somewhat consistent world wide. The layers up to that point while varying in thickness are laid out in fairly even beds over the entire crust, as a general rule.Correct me if I'm Wrong.>> There is not basis for this statement, if I'm reading it corrrectly. In fact, while at the Grand Canyon, you were looking at a good example of just the opposite, with the Schist layers (the dark rock through which the river runs, as they say in the movies<g> are not layered nice and horizontal and even like the rocks above, but are all jumbled up and messy. Also, among the strata that look well layered from the area of the visitor center, but down canyon some ways, there is also a lot of messiness among the strata, in particular in association with lava flows, if I remember my GC geology correctly. Someone with more info on this may want to chime in here. <<The variations in the layers represent different stages of the solar output.>> Solar output of sandstone and limestone? Not too likely! << I believe there was a hugh catastrophe that occurred to the earth at that time.>> At which time? << What other theories are there for these organized layers and the mess of layers above this layer. << Well, things are not laid out as you thought, partly thanks to some misinformation from a rogue park ranger! Hope this helps. Cheers, GTL – Greg Laden, Written 14-Aug-1994 @ 20:10:00 Using: Windows NavCIS PRO 1.25