About the last group activity, if an igneous rock layer is between 2 sedimentary rock layers of same composition, does that mean the igneous rock must be an intrusuion?

-- Amanda Fields (fields@oswego.edu), April 03, 2001

Answers

I explained the reasoning behind figuring out the relative ages of sedimentary rocks and the intrusion in that exercise in a previous question. Please read it.

Recall that in Chapter 4 you learned that a "sill" is a type of igneous intrusion. The igneous rock on the exercise was labeled a "diabase sill."

-- Sharon Gabel (gabel@oswego.edu), April 03, 2001.