Questions: While on a geologic expedition, you unearth a large, dark stone with an excellent print of a fossil embedded within the rock. Because of the dark color, your friend automatically assumes that it is an igneous rock. Explain why it is uncommon to find fossils in igneous rock.

The answer is: It is uncommon to find fossils in igneous rock because fossils typically form in sedimentary rocks.

Explanation:

1. Formation Process: Fossils are the preserved remains or traces of organisms that lived in the past. They are most commonly found in sedimentary rocks because these rocks form from the accumulation and compaction of sediments, which can include organic material. Over time, these sediments can bury and preserve the remains of organisms, leading to fossilization.

2. Igneous Rock Characteristics: Igneous rocks form from the cooling and solidification of magma or lava. This process involves extremely high temperatures, which would destroy any organic material. As a result, it is highly unlikely for fossils to survive the formation of igneous rocks.

3. Sedimentary Rock Environment: Sedimentary rocks often form in environments where organisms live, such as rivers, lakes, and oceans. These environments are conducive to the accumulation of sediments and the preservation of fossils. In contrast, igneous rocks form from volcanic activity, which is not typically associated with environments where organisms are buried and preserved.

In summary, the high temperatures involved in the formation of igneous rocks make it uncommon for fossils to be found in them, as these conditions would destroy any organic material. Fossils are more commonly found in sedimentary rocks, where conditions are favorable for their preservation.