10.2 The Geology of Venus
3 min read•june 12, 2024
Venus, Earth's fiery twin, boasts a landscape of vast plains and towering highlands. Its surface, peppered with impact craters, tells a tale of periodic global events. This unique geological history sets Venus apart from other terrestrial planets.
Volcanic activity on Venus mirrors Earth's, but with key differences. The extreme heat and pressure shape distinctive features like and . Venus' hellish conditions, including toxic air and scorching temperatures, create a hostile environment unlike any in our solar system.
Venus' Geological Features and Surface Conditions
Surface features of Venus
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- Plains cover about 80% of Venus' surface consisting of relatively smooth and flat areas (, )
- Highlands are elevated regions on Venus' surface that include mountains, plateaus, and tesserae which is deformed terrain (, )
- Impact craters formed by meteoroid impacts on the surface are fewer in number compared to other terrestrial planets (, )
Crater distribution and surface age
- used to estimate the age of a planetary surface where older surfaces have more craters and younger surfaces have fewer craters
- Venus has a relatively uniform distribution of craters across its surface suggesting the entire surface is roughly the same age
- Estimated age of Venus' surface is around 300-600 million years old which is relatively young compared to other terrestrial planets (Mars, Mercury)
- The relatively young surface age suggests periodic global resurfacing events on Venus
Venus vs Earth: Volcanic activity
- Similarities between Venus and Earth:
- Both planets experience and activity
- Presence of volcanoes, , and tectonic features on both planets
- Differences between Venus and Earth:
- Venus has a higher surface temperature and pressure than Earth affecting the behavior of magma and lava flows
- Venus lacks , unlike Earth, as Venus' crust is a single, continuous plate
- Venusian volcanoes are generally larger and fewer in number compared to Earth's volcanoes
- Tectonic features on Venus, such as tesserae and coronae, are unique to the planet
Extreme conditions on Venus
- High surface temperature with an average of 462℃ (864℉) caused by the extreme in Venus' atmosphere
- High atmospheric pressure about 90 times that of Earth's equivalent to the pressure found 1 km deep in Earth's oceans
- Toxic atmosphere primarily composed of carbon dioxide (96%) and nitrogen (3%) with traces of sulfuric acid and other corrosive compounds
- Lack of liquid water on the surface due to the high temperature and pressure conditions
- Absence of a magnetic field leaves the surface exposed to harsh solar radiation and charged particles from the solar wind
Venus' Geological Processes
- : The extreme surface temperature on Venus is primarily caused by the greenhouse effect, where the dense atmosphere traps heat from the Sun
- Plate tectonics: Unlike Earth, Venus lacks active plate tectonics, which affects its geological processes and surface features
- Venus' : The planet's thick, rigid outer layer plays a crucial role in its geological activity and surface characteristics
Key Terms to Review (19)
Aphrodite Terra: Aphrodite Terra is a major highland region on the planet Venus, named after the Greek goddess of love and beauty. It is one of the most prominent features on the Venusian surface and provides important insights into the geology and evolution of this Earth-like planet.
Atmospheric Composition: Atmospheric composition refers to the mixture of gases that make up the atmosphere surrounding a planet or other celestial body. This term is particularly relevant in the context of understanding the geology and environmental conditions of Venus, as the composition of its atmosphere is a key factor in determining the planet's surface features and habitability.
Cleopatra Crater: The Cleopatra Crater is a prominent impact crater located on the surface of Venus, named after the famous Egyptian queen Cleopatra. It is an important geological feature that provides insights into the history and evolution of the planet's surface.
Coronae: Coronae are circular or elliptical features found on the surface of Venus, characterized by a central dome or uplift surrounded by concentric fractures or troughs. These unique geological structures provide insights into the interior dynamics and tectonic processes of the planet.
Crater Density: Crater density refers to the number of craters per unit area on the surface of a planetary body. It is a measure of the impact history and geological activity of a planet or moon, providing insights into its formation and evolution.
Greenhouse effect: The greenhouse effect is the process by which certain gases in a planet's atmosphere trap heat, leading to an increase in surface temperatures. These gases allow sunlight to enter but prevent some of the resulting heat from escaping back into space.
Greenhouse Effect: The greenhouse effect is a natural process that warms the Earth's surface by trapping heat from the sun in the atmosphere. It is a crucial mechanism that maintains the planet's temperature and makes it habitable for life, but human activities have intensified this effect, leading to global climate change.
Guinevere Planitia: Guinevere Planitia is a large lowland region on the surface of Venus, located in the planet's northern hemisphere. It is one of the most prominent features on the Venusian landscape, characterized by its relatively smooth and flat terrain.
Ishtar Terra: Ishtar Terra is a large highland region on the planet Venus, located in the northern hemisphere. It is one of the most prominent and geologically complex features on the surface of Venus, characterized by its high elevation and diverse geological structures.
Lava Flows: Lava flows are the surface expression of molten rock that has been erupted from a volcanic vent or fissure and moved downslope under the influence of gravity. They are a fundamental feature of volcanic landscapes, shaping the terrain and influencing the overall geology of a region.
Lavinia Planitia: Lavinia Planitia is a vast, low-lying region on the surface of Venus, characterized by its relatively smooth and featureless terrain. It is located in the northern hemisphere of the planet and covers an area approximately the size of the state of Texas.
Lithosphere: The lithosphere is the outermost solid shell of a rocky planet, including Earth. It is composed of the crust and the uppermost portion of the mantle, and it is characterized by its rigidity and strength, which sets it apart from the underlying, more ductile asthenosphere.
Mead crater: The Mead crater is a large impact crater located on the surface of Venus, named after the American anthropologist Margaret Mead. It is one of the most prominent features on the planet's surface, providing insights into the geological history and processes of Venus.
Plate Tectonics: Plate tectonics is the scientific theory that describes the large-scale motion of the Earth's lithosphere, which is divided into several rigid plates that move independently over the more fluid asthenosphere. This concept is fundamental to understanding the global perspective, the structure of Earth's crust, the evolution of life and climate, and the geology of other terrestrial planets in our solar system.
Resurfacing: Resurfacing refers to the process of modifying or renewing the surface of a planetary body, often through volcanic activity, tectonic forces, or other geological processes. It is a key concept in understanding the geology and evolution of planetary surfaces, particularly in the context of Venus.
Tectonic: Tectonic refers to the structure and movement of a planet's lithosphere, which includes its crust and upper mantle. These movements can lead to various geological features and activities such as mountain formation, earthquakes, and volcanism.
Tessera: A tessera is a distinct, polygonal, tectonic block on the surface of the planet Venus. These features are unique to Venus and are believed to be the result of complex geological processes that have shaped the planet's surface over time.
Tessera are found primarily in the highlands of Venus and are characterized by their complex, intersecting patterns of ridges and valleys, which give them a distinctive, 'tesselated' appearance. They are thought to be some of the oldest features on the Venusian surface, formed during the early stages of the planet's geological evolution.
Tesserae: Tesserae are the individual polygonal tiles that make up the distinctive surface features on the planet Venus, known as the tesserae terrain. These tiles are typically composed of deformed and fractured rock and are a key characteristic of the geology of Venus.
Volcanism: Volcanism refers to the processes and phenomena associated with the eruption of molten rock, called magma, from the interior of a planetary body onto its surface. This term is central to understanding the composition, structure, and evolution of planets within our solar system.