Updated Articles and Resources

By Andrew Alden, About.com Guide since 1997

Folk's Classification of Sediments Created: Sunday, June 02, 2013 Updated: Monday, June 17, 2013
Triangular diagram to classify sediments by their sand, silt and clay content into categories specified by Folk.
Now Let Us Praise Famous Stones Created: Friday, February 06, 2004 Updated: Sunday, June 16, 2013
Real rock stars from around the world, from Plymouth Rock to the Blarney Stone to the Black Stone of the Ka'aba.
Alkali Feldspar in Granite Pegmatite Created: Sunday, June 16, 2013 Updated: Sunday, June 16, 2013
Large alkali feldspar crystals in a boulder in Albany, New York. Page 7.
Treating Rocks and Fossils with Hydrochloric Acid Created: Saturday, June 15, 2013 Updated: Saturday, June 15, 2013
Step-by-step description of using HCl to dissolve rocks and clean fossils.
Waste Glass Created: Tuesday, June 11, 2013 Updated: Tuesday, June 11, 2013
Waste glass is a common form of artificial rock. Page 21.
Artificial Rocks Gallery Created: Tuesday, February 13, 2007 Updated: Tuesday, June 11, 2013
Bricks, mortar, concrete, plaster and other artificial rocks.
Celadonite Created: Wednesday, June 05, 2013 Updated: Wednesday, June 05, 2013
Celadonite is a mica mineral well known to artists.
Cement and Concrete Created: Saturday, September 09, 2006 Updated: Wednesday, June 05, 2013
Cement is an artificial stone--or maybe lava.
Aquamarine Created: Thursday, January 29, 2009 Updated: Monday, June 03, 2013
Aquamarine is the state gem of Colorado.
Piemontite Created: Monday, June 03, 2013 Updated: Monday, June 03, 2013
Piemontite is one of the silicate minerals, related to epidote.
The Silicate Minerals Created: Sunday, May 03, 2009 Updated: Monday, June 03, 2013
The great majority of rocks are made of silicate minerals.
Sedimentary Rock Classification Diagrams Created: Thursday, February 19, 2009 Updated: Monday, June 03, 2013
Diagrams to help classify sedimentary rocks.
Ternary Diagram for Sandstone and Mudstones Created: Thursday, February 19, 2009 Updated: Monday, June 03, 2013
Ternary diagram to classify sandstone and mudstones.
Quick Sediment Testing: Particle Size Created: Wednesday, May 29, 2013 Updated: Monday, June 03, 2013
A simple procedure for analyzing the grain-size composition of sediment.
Folk's Classification of Gravelly Sediments Created: Friday, May 31, 2013 Updated: Saturday, June 01, 2013
Triangular diagram to classify sediments by their sand, gravel and fine-grained content into categories specified by Folk.
Classification of Gravelly Sediments Created: Friday, May 31, 2013 Updated: Friday, May 31, 2013
Schlee's modification of the Shepard scheme for gravelly sediments.
Shepard's Classification of Sediments Created: Friday, May 31, 2013 Updated: Friday, May 31, 2013
Triangular diagram to classify sediments by their sand, silt and clay content into categories specified by Shepard.
Soil Classification Diagram Created: Friday, May 31, 2013 Updated: Friday, May 31, 2013
Triangular diagram to classify soils by their sand, silt and clay content.
Archean Slate in Minnesota Created: Tuesday, May 28, 2013 Updated: Tuesday, May 28, 2013
An About.com Geology reader presents an ancient slate locality.
Troctolite Created: Sunday, May 26, 2013 Updated: Sunday, May 26, 2013
Troctolite is one of the gabbroid rocks: igneous, plutonic and mafic.
Igneous Rock Types Created: Friday, February 27, 2009 Updated: Sunday, May 26, 2013
The major igneous rock types, plutonic, intrusive and extrusive.
Pleistocene Fossils of the Fairmead Landfill Site Created: Saturday, May 25, 2013 Updated: Saturday, May 25, 2013
A major collection of Irvingtonian fossils is growing near Fresno.
Eternal Flame Falls, Chestnut Ridge Park Created: Thursday, March 25, 2010 Updated: Friday, May 24, 2013
Eternal Flame Falls in Chestnut Ridge Park is one of New York state's geological attractions.
Deep Earthquakes Created: Saturday, March 19, 2005 Updated: Friday, May 24, 2013
Deep-focus quakes aren't supposed to happen, but they do.
Provincial Time Terms Created: Sunday, May 19, 2013 Updated: Sunday, May 19, 2013
Not all geologic time units are settled and universal.
The JMA Earthquake Scale Created: Saturday, May 18, 2013 Updated: Saturday, May 18, 2013
Details of the modern Japanese seismic intensity scale.
The Comeback of Noah's Flood Created: Saturday, February 06, 2010 Updated: Thursday, May 09, 2013
Once flame-war fuel in the 1800s, the bibilical flood story of Noah is now just another marvel of modern science.
Geologic Gift Ideas Created: Saturday, October 21, 2006 Updated: Thursday, May 09, 2013
A few suggestions for something to get your favorite geologist.
The Rise of Erosion Created: Friday, March 31, 2006 Updated: Thursday, May 09, 2013
This old standby of the old geology is back on today's scientific cutting edge.
Connecticut Geology Created: Tuesday, March 14, 2006 Updated: Thursday, May 09, 2013
Born-and-bred Westerners may find that Connecticut's laid-back landscape is way cool.
A Research Cruise in Alaska, 1979 Created: Thursday, September 15, 2005 Updated: Thursday, May 09, 2013
Pictures, reminiscences and information about a research cruise by the USGS in 1979.
A Day in the Mohawk Valley and Finger Lakes, New York Created: Friday, August 19, 2005 Updated: Thursday, May 09, 2013
A day's drive from Albany to Ithaca and back covers the geology of the Mohawk Valley and Finger Lakes of New York.