Bedform Sedimentology Studies Information about ripples, dunes, and sedimentary structures including, explanatory text, computer-generated images and movies, photographs, and bedform-simulation software provided by the USGS. http://walrus.wr.usgs.gov/seds/
Low–temperature formation of Dolomite and Magnesite Latest version (2005) of the open-access e-book authored by J.C. Deelman on dolomitization and related phenomena. A total of 505 text pages, including a number of graphs, drawings and photographs. http://www.jcdeelman.demon.nl/dolomite/bookprospectus.html
Petrology of sedimentary rocks Although long out of print, the seminal book (a total of 182 pages in a single pdf file) by R.L. Folk (1974) remains an excellent resource if you are interested in sedimentary rocks. http://www.lib.utexas.edu/geo/folkready/
Schlumberger Oilfield Glossary With more than 4600 entries it constitutes an instant technical reference for both the generalist and the expert oil geologist http://www.glossary.oilfield.slb.com/
Help build the largest human-edited directory on the web.