Question

How were mountains thought to be formed (a) by contractionists and (b) by permanentists?

Short answer

Contractionists thought mountains formed by Earth's cooling and contracting, while Permanentists believed mountains always existed in their current form.

Step-by-step solution

- Understand Contractionist Theory

Contractionists believed that mountains were formed due to the Earth cooling and contracting. As the Earth cooled, the outer crust would wrinkle and fold, leading to the creation of mountain ranges.

- Understand Permanentist Theory

Permanentists thought that mountains were always present on Earth since its formation. They believed that mountains did not significantly change in size or shape over geological time periods, maintaining their current form.

Key concepts

Contractionist Theory

The Contractionist Theory suggests that mountains formed as a result of the Earth cooling and contracting over time. Imagine a grape turning into a raisin. As the Earth cooled, its outer crust would wrinkle and fold, much like the skin of a drying fruit. This wrinkling and folding created the mountain ranges we see today.

This theory was popular in the 19th century and provided a simple explanation for the Earth's rugged landscape. However, it didn't account for the actual geological processes that we now understand better.

Permanentist Theory

The Permanentist Theory is quite different from the Contractionist view. Permanentists believed that mountains have always been present on Earth since its formation. They thought that these mountains did not undergo significant changes in their size or shape over long periods of time.

Essentially, the Permanentist Theory posits that mountains are a permanent fixture of the Earth's surface. Unlike the Contractionist Theory, this view suggests a more stable and unchanging Earth, rather than one that is constantly evolving.

Modern geology has shown that this theory is not entirely accurate, as mountains do undergo changes due to processes like erosion, volcanic activity, and tectonic movements.

Geological Time Periods

Geological time periods provide a framework for understanding the Earth's history and the processes that have shaped its surface. These time periods are divided into eons, eras, periods, epochs, and ages, spanning billions of years.

Here's a brief overview of the major divisions:

• Eons: The largest time units, encompassing major stages in Earth's history.
• Eras: Subdivisions of eons, characterized by significant events like mass extinctions.
• Periods: Subdivisions of eras, often named after geographic regions or prominent characteristics (e.g., Jurassic Period).
• Epochs: Smaller divisions of periods, marked by notable changes in climate and life forms.

Understanding geological time periods helps in studying Earth's dynamic processes. It reveals that mountains and other geological features change over time, influenced by forces like plate tectonics and erosion.

These insights debunk outdated theories like the Permanentist Theory and emphasize the transforming nature of Earth's landscape.