It is with carbonate rocks that we see most distinctly that life is a geological process (trademarked, all rights reserved). The large majority of carbonate sediments are directly derived from living systems, and as such they are excellent indicators of past depositional environments. You will want to see these ultimate mineralogy pages for calcite, aragonite and dolomite. For simple introductions to carbonate sedimentology, visit the excellent carbonate pages from the Texas Bureau of Economic Geology. (They have nice online review questions!) As we approach more detailed carbonate topics, please visit the Wikipedia page on carbonate biomineralization, and this one on carbonate classification. There are some good photomicrographs of carbonate rocks (and others) on this Oxford University webpage. And we must take a field trip to the Bahamas someday, but for now we have to do it virtually!
Here is your Second Essay Assignment (due 7:30 am, Thursday, February 27, in your Dropbox folder).
Geology in the News –
A new articulated skeleton of a Neanderthal was recently found in Iraq — the first such skeleton to be found in over a decade. The locality is in Iraqi Kurdistan, so you can imagine how difficult it is to work there.
Here’s an analysis of a cool reconstruction of the orthoceratoid nautiloid Endoceras. It’s not often we’re told the reasons behind this type of art/science.
Using carbon and oxygen stable isotope ratios in fossil eggshells, paleontologists show strong evidence that dinosaurs were endothermic.