Question

Which term describes the dark, flat areas on the Moon's surface which are made of cooled, hardened lava? A. spheres C. highlands B. moonquakes D. maria

Short answer

The correct answer is D. maria.

Step-by-step solution

Understanding the Question

The question asks us to identify the term that describes specific features on the Moon's surface. The key characteristics to note are 'dark, flat areas' and 'made of cooled, hardened lava.'

Reviewing the Options

We have four options to evaluate: A. spheres, C. highlands, B. moonquakes, and D. maria. Each of these terms needs to be considered against the characteristics given in the question.

Evaluating Each Option

- Option A: 'Spheres' does not align with any known geological term related to the Moon's surface. - Option B: 'Moonquakes' refer to seismic activities on the moon, unrelated to surface features. - Option C: 'Highlands' usually refer to elevated areas, not flat ones. - Option D: 'Maria' are known as large, dark plains on the moon, formed by ancient volcanic eruptions, matching the description provided.

Final Decision

Given that 'maria' (option D) are large, dark, flat areas on the Moon created by ancient volcanic activity, this is the correct term matching the description in the question.

Key concepts

Maria

The term "maria" describes large, dark, flat areas on the surface of the Moon. These regions are not seas of water but were named "maria," which is Latin for "seas," by ancient astronomers who mistook them for bodies of water. Instead, these areas are vast basaltic plains formed by ancient volcanic eruptions. The lava that erupted during these events spread across the lunar surface, filling in craters and depressions, leading to the smooth, flat appearance we see today.
The maria are significantly darker than the surrounding highlands due to their composition of iron-rich basalts. These iron-rich rocks absorb more sunlight, making the mare regions appear darker when viewed from Earth. Key features of maria include:

• Formation by volcanic activity
• Primarily located on the Moon's near side
• Composed mainly of basalt
• Relatively younger than lunar highlands

Studying the maria allows scientists to gain insights into the Moon's volcanic history and the solar system's evolution.

Lunar Geology

Understanding lunar geology involves studying various aspects of the Moon’s surface and its composition. The Moon provides a record of some of the oldest geological processes, offering a window into Earth's past and the early solar system formation. Lunar geology examines:

• The structure and composition of lunar crust, mantle, and core
• The impact craters that dominate the landscape
• The presence of maria and highlands
• Soil characteristics, known as regolith

The Moon's surface is predominantly covered in regolith, a layer of dust and broken rock, formed by the constant barrage of meteoroids over millions of years. This surface layer helps scientists understand the impact history of the solar system. Moreover, lunar rocks returned by Apollo missions have shown unique mineral compositions, unveiling the Moon's diverse geological features. The differences in surface features between maria and highlands give clues to the Moon’s volcanic and tectonic past.

Volcanic Activity on the Moon

Volcanic activity on the Moon plays a crucial role in shaping its landscape. The Moon doesn’t have active volcanoes today, but evidence of past eruptions is clear in the extensive lava flows that created the maria. These eruptions mainly occurred billions of years ago during the Moon's early geological history.
Unlike Earth, lunar volcanoes did not form tall mountains but rather released lava that flowed over large areas. This difference is due to the Moon's lower gravity and lack of a thick atmosphere, allowing lava to flow more easily and spread thinly over the surface. Characteristics of lunar volcanic activity include:

• Basaltic lava eruptions
• Creation of large plains (maria)
• Few, if any, visible volcanic structures like cone-shaped mountains

Such activity has ceased for millions of years, leaving a static landscape that contrasts with Earth’s dynamic geology. The study of lunar volcanic activity provides valuable insights into volcanic processes on planets and moons without atmospheres, helping to compare planetary formation and evolution within our solar system.