Final answer:
Fissures are not simply small cracks of stress in an exposed surface, as they can be quite large and significant in geology. They refer to extensive cracks or fractures, such as volcanic or tectonic fissures, that are different from faults which involve significant rock movement.
Step-by-step explanation:
The statement that fissures are small cracks of stress in an exposed surface is false. Fissures are, in fact, often quite large and can be significant features in geological formations. In geology, a fissure is an extensive crack or fracture in rocks, where movements have likely occurred along the fracture. This can be seen in the division of the Earth's crust into different tectonic plates, and such movements along fissures are a critical part of the plate tectonics process.
In certain contexts, such as structural geology, the term fissure is particularly used to describe a wide crack or opening in rock formations often caused by the Earth's tectonic activity, such as volcanic fissures from which lava erupts. These can be much larger than what could be described as 'small cracks.' For example, the Great Rift Valley in Eastern Africa is a massive fissure in the Earth's crust caused by tectonic forces. Moreover, in medical terminology, a fissure can refer to a deep groove or opening in organs, such as the fissures found in the brain's structure.
It's also important to distinguish between fissures and faults, as faults are the result of significant movement of rocks and are usually single fractures, whereas fissure can refer to a variety of cracks of different sizes and significance, not necessarily associated with a fault's movement.