AboutDr Thomas Bell Expertise I can answer questions regarding surface earth processes and the chemical transformations that sediments and rocks undergo with burial. I can also answer questions regarding deep time, the evolution of the elements, and the last 4.5 billion years of earth history. I specialize in metallic ore forming processes, the major geologic time periods when they were produced and what they tell us about the evolution of our planet. Learn more about my professional interests at Stratamodel.com.
Experience I am a professional consulting geologist with a background in the petroleum, mining, environmental, and geotechnical industries with over 25 years of experience.
Education/Credentials Ph.D., Geology, University of California at Berkeley, 1984
M.A., Geology, University of California at Berkeley, 1980
B.S., Geology, San Jose State University, 1978
Question How do geologists in the field find clues about the distribution of rock types if they are buried deep under vegetation?
Answer Annette,
Soil and vegetation obscure bedrock over most of the continents. Never the less, geologists are trained to 'see through' the cover. We have lots of tricks of the trade that give us hard evidence or strong clues to the composition of underlying bedrock.
Sometimes the vegetation itself says a lot about the bedrock. An extreme example might be so called cobalt plants which are just about the only plant to thrive were the cobalt content of the soil is elevated. This is a nice trick to use when exploring for sources of cobalt. Distinct bedrock formations may hold different amounts of water so vegetation over porous rocks could be quite different than that over less porous rocks.
Bedrock exposure can be extrapolated under soil and vegetation. Often, rock chips in soil can be linked to the underlying bedrock and an observant geologist can trace the extent of these chips or what we call 'float' to deduce the underlying source. The soil that form by bedrock disintegration during chemical weathering also provides a rich source of information regarding the parent material.
When we really want to know whats down there, we can always dig a hole, cut a trench, or drill.
