Chapter 3, Problem 1RQ

To determine

The conditions that favor the preservation of fossils such as soft parts of the ancient organism within the sediment.

Answer to Problem 1RQ

Low permeability of oxygen in sediments, inorganic materials that fill the spaces left inside the cell wall, formation of replicas of imprints are some conditions that favor the preservation of soft parts as fossils within the sediment.

Explanation of Solution

Fossils are the remains of ancient organisms that are preserved for thousands or millions of years. Conditions that favor the preservation of soft parts as fossils within sediment are as follows:

(i) Soft parts of organisms such as skin impressions are to be preserved in sediments that contain oily, water-repellent, or organic matter.

(ii) Protection from oxygen is the main condition required to preserve the soft tissues of organisms.

(iii) After the plants buried in sediment, inorganic materials may be used to fill the spaces left inside the cell wall of plant tissue. This process is known as permineralization.

(iv) In some conditions, fossils get dissolved by the solutions percolating through sediment and leave space within the rock that is a three-dimensional negative imprint of the organic structure of fossils. This three-dimensional structure is known as mold. Geologists are able to make the replica of mold and these replicas are known as impressions.