Lunar Maria

Definition

Lunar maria are the large, dark, flat areas on the surface of the Moon. They are solidified basaltic lava flows that filled in large impact basins created by asteroid and comet impacts in the Moon's distant past.

5 Must Know Facts For Your Next Test

1. Lunar maria cover approximately 16% of the Moon's surface and are concentrated on the near side, facing the Earth.
2. The maria appear dark in color because they are composed of basaltic lava, which is darker than the surrounding lunar highlands.
3. The largest lunar mare is the Oceanus Procellarum, which covers over 4 million square kilometers on the Moon's western near side.
4. Lunar maria formed between 3.5 and 1.2 billion years ago, during a period of intense meteorite bombardment known as the Late Heavy Bombardment.
5. The lower crater density in the maria compared to the lunar highlands indicates that the maria are younger geological features on the Moon.

Review Questions

• Explain how the lunar maria relate to the general properties of the Moon.
  • The lunar maria are a key feature of the Moon's surface that provide important information about its geological history and evolution. The dark, basaltic lava flows that fill the large impact basins on the Moon's surface are a stark contrast to the lighter-colored, heavily cratered lunar highlands. The distribution and characteristics of the maria, such as their lower crater density, reveal that they formed relatively recently compared to the older highlands, during a period of intense meteorite bombardment known as the Late Heavy Bombardment.
• Describe the role of impact basins in the formation of the lunar maria.
  • The lunar maria were formed by the filling of large impact basins on the Moon's surface with basaltic lava. These impact basins were created by the collision of massive asteroids or comets with the lunar surface during the Moon's early history. The intense impact events fractured and depressed the lunar crust, creating low-lying regions that were later flooded by molten basaltic lava erupting from the Moon's interior. This process of impact basin formation and subsequent lava filling is a key factor in the origin and distribution of the lunar maria across the Moon's surface.
• Analyze how the characteristics of the lunar maria, such as their lower crater density, provide insights into the Moon's geological evolution.
  • The lower crater density observed in the lunar maria compared to the surrounding highlands indicates that the maria are younger geological features on the Moon. This suggests that the maria formed relatively recently, during a period of decreasing meteorite bombardment after the intense Late Heavy Bombardment era. By studying the crater density and other features of the maria, scientists can piece together a timeline of the Moon's geological history, including the timing and processes involved in the formation of the large impact basins and their subsequent flooding by basaltic lava flows. This information helps us better understand the Moon's origin, internal structure, and the dynamic geological processes that have shaped its surface over billions of years.

Related terms

Impact Basins: Large, circular depressions on the lunar surface formed by the impact of large asteroids or comets during the Moon's early history.

Basaltic Lava: A type of fluid, low-viscosity lava that is rich in iron and magnesium and typically erupts at high temperatures.

Crater Density:

The number of impact craters per unit area on the lunar surface, which provides information about the age and geological history of different regions.