Astronomy Practice Exam 2025 - Free Astronomy Practice Questions and Study Guide

The surface of Mars is characterized by the presence of canyons and valleys, which are some of its most distinctive geological features. One of the most famous canyons on Mars is Valles Marineris, which is over 4,000 kilometers long and reaches depths of up to 7 kilometers. This extensive canyon system showcases the planet's history of geological activity, including erosion and tectonic processes.

Additionally, there are many valleys on the Martian surface that hint at past water flow, suggesting that liquid water may have once existed there. This evidence leads scientists to study Mars as a planet that may have had conditions suitable for life in its ancient past.

Unlike the other options provided, the Martian surface is not characterized by environments such as dense forests or oceans of liquid water, as these do not exist on Mars due to its thin atmosphere and cold temperatures. Although there are polar ice caps, the presence of large icebergs is not a defining feature of Mars' surface. The focus on canyons and valleys highlights the unique and intriguing geologic landscape that Mars possesses.