ASBOG Practice Exam

What feature can be used to narrow down the relative age of a geological sample?

1. Number of fossils within a sample

2. Type of rock composition

3. Presence of minerals

4. Geographical location

The correct answer is: Number of fossils within a sample

The number of fossils within a sample is an effective feature for narrowing down the relative age of geological samples through a method known as biostratigraphy. Fossils can provide critical information about the age of the rocks in which they are found because certain organisms existed during specific geological time periods. By identifying and counting the fossils, geologists can correlate rock layers with known fossil records, allowing them to estimate the relative ages of the samples. For instance, if a rock sample contains fossils of a species known to have existed during the early Mesozoic era, geologists can reasonably suggest that the rock itself is from that time period or later. This technique relies heavily on established fossil records, which serve as a chronological framework for interpreting the geological history of an area. The type of rock composition, while informative, does not provide direct insight into the relative age as effectively as fossils do, since rock types can persist over vast periods. The presence of minerals can indicate conditions of formation but is not a definitive age marker, and geographical location alone does not correlate with age without further context from the surrounding geological formations or fossil content.