GEOL 101 Lecture 31: Geo 101 Lecture 31

3 Pages
Unlock Document

GEOL 101
Paul Giesting

Wednesday, April 12, 2017 Lecture 31 Geochronology- Age of Rocks and Fossils - Geologic Record the fact that Earth has changed through time has become clear based on evidence • in the geologic record • geologic record is the record of events preserved in rocks - although all rocks are useful in deciphering the geologic record, sedimentary rocks are especially useful - learning to better interpret the record is still going on - Stratigraphy • surfaces known as bedding planes separate individual strata from one another (or the strata grade vertically from one rock type to another) • rocks above and below a bedding plane differ in composition, texture, color, or a combo of these features • bedding plane signifies - rapid change in sedimentation - period of non deposition - Superposition • Nicholas Steno realized he could determine the relative ages of horizontal strata be their position • in deformed strata, the task is more difficult • some sedimentary structures and some fossils allows geologists to resolve these kinds of problems - Age of lava flows, sills • determining relative ages of lava flows, sills, and associated sedimentary rocks uses alteration by heat and inclusions • a lava flow forms in sequence with sedimentary layers 1 Wednesday, April 12, 2017 - Principle of Inclusions- inclusions or fragments in a rock are older than the rock itself - Sill- will heat the rocks above and below it - Unconformities • conformable strata are sequences of rocks in which deposition was more or less continuous • unconformities in sequences of strata represent times of non deposition and/or erosion that encompass long periods of geologic time • the rock record in any single locat
More Less

Related notes for GEOL 101

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.