Chapter 15, Problem 16STP

Summary Introduction

To explain:

The reason for fossil formation in wet environment rather than in dry environment.

Introduction:

A fossil is any preserved evidence of an organism. Plants, animals and even bacteria can form fossils. More than 99 percent of the species that existed have become extinct. Only a small percentage of these organisms are preserved as fossils. Nearly all fossils are formed in sedimentary rocks. They do not form in igneous or metamorphic rocks.

Answer to Problem 16STP

Fossil formation occurs more readily in wet environment because the sediment is constantly depositing on the dead organism. This prevents the organism from being exposed to air and getting decomposed. In water, the dead remains of the organism are covered and preserved by the sediments. In a dry environment, there is a chance of it being eaten or decomposed.

Explanation of Solution

Most organisms decompose before they have a chance to get fossilized. Only those organisms that get buried rapidly in sediment are readily fossilized. The process of fossil formation occurs more frequently with organisms that live in water because the sediment in aquatic environments is constantly settling, covering and preserving the remains of the organisms.

In the dry environment, the dead organism gets easily decomposed by bacteria and other organisms. They decay easily as the dead body is exposed to air and microbes. This prevents fossilization.