Which type of pluton is characterized as being smaller than 100 km²?

The answer identifies stocks as the correct type of pluton characterized by being smaller than 100 km². Stocks are small, relatively shallow intrusions that can be relatively small in size compared to batholiths, which are massive, large bodies often extending over 100 km². Stocks typically form from magma that has intruded into surrounding rock layers and crystallized beneath the Earth’s surface.

Understanding the distinctions among various plutonic structures helps clarify why stocks are classified as such. Batholiths, for instance, are significantly larger than stocks and typically form through the accumulation of multiple smaller intrusions over time. Sills and laccoliths are also classified based on different structural features and characteristics related to their intrusions within sedimentary layers or along the edges of existing rock formations, rather than their overall size.

This knowledge of the size and structure of geological formations is crucial in mining engineering, particularly when assessing resource location and extraction methods within different types of rock formations.