Relative Motion
Geological processes that affect Earth's surface can operate on very different time and spacial scales. Scientists use knowledge of Earth's processes to better understand other planets in the solar system. Scientists investigating Mars have observed similar features on both planets. The table describes some of the features.
Geologic Process Time scale Causes of Process on Earth Causes of Process on Mars
Mountain formation Millions of years Collisions betweens plates uplift millimeters of land per year Ancient volcanic eruptions and wind erosion
Landslides Seconds to hours Rock masses weakened by erosion slide down a mountain or cliff Rock masses weakened by erosion slide down a mountain or cliff
Volcanic eruptions Days to weeks Magma is released from a volcano Magma is released from a volcano
Earthquakes Seconds Seismic waves caused by slipping plates cause the ground to shake Long-term cooling of the planet causes seismic waves to shake the ground
Meteorite impacts Seconds A crater is formed when a meteorite crashes onto the surface A crater is formed when a meteorite crashes onto the surface
Formation of a canyon Thousands to millions of years Erosion from wind and flowing water carves out rock A fracture in the crust separates rock
Multiple Choice Question
The largest volcano on Earth is 10 km high and 120 km across. The largest volcano on Mars is 25 km high and 624 km across. Which best describes why the volcanoes on Mars are so much larger than those on Earth?
A.
The Earth has more mass, which makes magma from eruptions more spread out.
B.
Most of Earth's surface is covered in water, which prevents a volcano from erupting.
C.
Mars does not have moving tectonic plates, which allows lava to keep flowing in the same place.
D.
Mars' atmosphere is composed of mostly carbon dioxide, which encourages bigger volcanoes to form.
1 answer
The correct answer is:
C. Mars does not have moving tectonic plates, which allows lava to keep flowing in the same place.
This explanation is accurate because the lack of tectonic plate movement on Mars allows volcanic activity to occur in a single location for a longer period of time, resulting in the accumulation of larger volcanic structures. In contrast, Earth's tectonic activity tends to move volcanoes away from the hotspot of magma generation, limiting their size.
