Goals

By the end of this lab you will be able to:

1. Examine a sedimentary rock in and write a comprehensive description of its characteristics.

2. Differentiate the three major types of sedimentary rocks: clastic, chemical and biochemical.

3. Describe and name clastic and chemical sedimentary rocks.

4. Describe and name major sedimentary structures.

Introduction

Sedimentary rocks provide information on processes that occurred at the Earth’s surface during the past. They preserve a record of the Earth’s climate, atmosphere, oceans and life.  Geoscientists have carefully studied modern sediments to determine the nature of the physical or chemical processes that formed any particular modern sediment.  A sedimentary rock preserved in the geological record can then be compared to these modern sediments, and deductions made about the conditions under which the sedimentary rock was formed.  In following labs, you will learn how to reconstruct Earth’s history from the geological record.

The first step is to learn how to properly describe sedimentary rocks and sedimentary structures.  The two main elements used to classify sedimentary rocks are mineral composition and texture.  A third important element is the structures found within the rock, which are often the most telling features for determining the rock’s origins.