key term - Stock

Definition

In geology, a stock is a large, irregularly shaped body of intrusive igneous rock that has formed beneath the Earth's surface. Stocks are typically less than 100 square kilometers in area and are thought to be the remnants of magma that solidified after rising through the crust but did not reach the surface. Understanding stocks helps in identifying the processes of magma intrusion and the formation of various landforms associated with volcanic activity.

5 Must Know Facts For Your Next Test

1. Stocks can vary in composition, ranging from granitic to dioritic and gabbroic types, depending on the minerals present in the original magma.
2. The size and shape of a stock can influence the surrounding geological formations, often leading to the development of unique landforms and mineral deposits.
3. Stocks often serve as a source of valuable mineral resources, including copper, gold, and silver, due to the concentration of minerals during the cooling process.
4. The study of stocks contributes to understanding tectonic activity, as their formation is often associated with regions of crustal deformation or subduction zones.
5. Stocks can be identified in the field by their distinct features such as coarser grain size compared to surrounding rocks and their position within older rock formations.

Review Questions

• How does the formation of a stock relate to the processes involved in magma intrusion within the Earth's crust?
  • The formation of a stock is closely tied to the processes of magma intrusion. When magma rises through the crust, it may not always reach the surface, leading to the creation of stocks as the magma cools and solidifies underground. These irregularly shaped bodies are important for understanding how magma behaves within the Earth and how it can create various geological features as it interacts with surrounding rocks.
• What is the significance of stocks in terms of mineral resources and their impact on economic geology?
  • Stocks hold significant importance in economic geology because they can serve as sources for valuable mineral resources like copper, gold, and silver. As magma cools within a stock, certain minerals can crystallize and concentrate, making these areas prime targets for mining. The study of stocks helps geologists identify potential mining sites and understand the geological processes that lead to ore formation.
• Evaluate the role of stocks in shaping our understanding of tectonic processes and geological history.
  • Stocks play a crucial role in shaping our understanding of tectonic processes and geological history by providing insights into magma dynamics and crustal interactions. Their formation often occurs in tectonically active regions, such as subduction zones or rift systems, indicating past volcanic activity and contributing to our knowledge of how continental crust evolves over time. By studying stocks, geologists can reconstruct past geological events and assess the impact of tectonic forces on landscape evolution.

Related terms

Pluton:

A pluton is a general term for any body of intrusive igneous rock, including stocks and batholiths, that has solidified from magma beneath the Earth's surface.

Dike: A dike is a vertical or steeply inclined sheet of igneous rock that cuts across existing rock layers, formed by magma that has intruded into fractures.

Sill:

A sill is a horizontal sheet of igneous rock that forms when magma intrudes between existing rock layers, creating new layers of rock.