Introduction to Sedimentation and Stratigraphy


The sedimentary record at the Grand Canyon
Course goals: Sedimentary rock - rocks that form from the transported remains of preexisting rocks - constitute the majority of rocks occurring at Earth's surface. Indeed, although they may comprise 10% of the upper crust, they cover 90% of the surface. Also, because they form at or near the surface, they contain the most complete geologic record of ancient surface environments. Thus, their study reveals unique insights into: Arguably, sedimentary rocks have the greatest practical utility to humans of any geologic resource.

The goal of this course is to provide the student with the opportunity:

Above all, at the end of this course, when you are handed a sedimentary hand sample or shown a sedimentary outcrop, you ought to be able to say something intelligent about the environment in which the sediments were deposited.


B. Breeden notes on rock du jour
Rock du jour

Rocks du jour: Unlike hard rocks, so many variables go into sedimentary rocks that each rock is, essentially, an individual. Thus, sedimentology is fundamentally descriptive. Thus, to develop your descriptive skills, each lecture will highlight either a rock du jour (rock of the day) that will be described and used to illustrate important concepts in sedimentary geology, or a link to a photograph of an outcrop du jour. These may show up on later tests, so make sure to take notes on their characteristics and the discussion issues they highlight. Unless otherwise indicated, current rocks du jour will be available for study during business hours in the lab room.

Analysis of Sedimentary Rocks: We approach sedimentary rocks in two sequential stages:

Description of sedimentary rocks:

This comes first, establishing the basic physical facts about the specimen before interpretation is attempted.

Sedimentary rock interpretations:

These go beyond the rock, itself, to establish its connections to a broader geologic picture. This invokes a number of key concepts.

A modest example