Hesperian

The Hesperian is a significant geologic system and time period on the planet Mars. During this time, Mars experienced widespread volcanic activity and massive flooding that created huge outflow channels on its surface. The Hesperian marks a transition from the wetter, possibly warmer world of the Noachian period to the dry, cold planet we see today.

This period began after the end of the Late Heavy Bombardment, roughly around 3700 million years ago, and likely ended between 3200 and 2000 million years ago. As heavy impacts decreased, volcanism became the main geological process, forming vast plains of flood basalts and beginning the formation of large shield volcanoes like Olympus Mons.

Volcanic activity released gases such as sulfur dioxide (SO₂) and hydrogen sulfide (H₂S), changing the way water weathered the planet’s surface. Later in the Hesperian, as the atmosphere thinned and the planet cooled, deep groundwater sometimes burst through the frozen ground, creating enormous floods that carved wide channels and possibly formed large lakes or an ocean in the northern hemisphere.

Description and name origin

The Hesperian System and Period is named after Hesperia Planum, a highland area near the large Hellas basin on Mars. This area features rolling plains with many ridges, similar to patterns seen on the Moon. These ridges are thought to come from ancient lava flows that poured out from cracks in the planet's surface. The Hesperian period covers a big part of Mars, especially in areas like Hesperia Planum and Syrtis Major Planum.

Hesperian chronology and stratigraphy

Martian time periods are based on studying the planet's surface from spacecraft images. Scientists look at areas with different textures, colors, or shapes to understand the history of Mars. These areas help them create a timeline of the planet's past.

The Hesperian is one of these time periods on Mars. It comes after the Noachian period and before the Amazonian period. During the Hesperian, Mars changed from a wetter world to the dry planet we see today. Scientists use clues like craters to figure out the age of different surface areas on Mars.

Mars during the Hesperian Period

The Hesperian was a time when Mars saw less frequent impacts from space, lots of volcanic activity, and huge floods. Many of the big cracks and folds on Mars formed during this period. The weight of a giant uplift called the Tharsis Bulge caused the surface to break and twist, creating long fractures and ridges. The massive canyon system known as Valles Marineris also formed because of these forces. As Mars became drier, sulfuric acid on the surface created many sulfate minerals.

During the Hesperian, scientists also found the first signs that Mars had glaciers and other ice-related processes. The Hesperian started with impact rates much higher than today, but these rates dropped over time, eventually becoming closer to what we see now.

Notes and references

This section contains references and notes that support the information provided in the article. It includes citations and sources used to verify the facts about the Hesperian period on Mars. For detailed references, readers should consult the original sources.

Bibliography and recommended reading

Here are some great books to learn more about Mars:

• Boyce, Joseph M. (2008). The Smithsonian Book of Mars) 978-1-58834-074-0.
• Carr, Michael H. (2006). The Surface of Mars. Cambridge, UK: Cambridge University Press. ISBN 978-0-521-87201-0.
• Hartmann, William K. (2003). A Traveler's Guide to Mars: The Mysterious Landscapes of the Red Planet) 0-7611-2606-6.
• Morton, Oliver (2003). Mapping Mars: Science, Imagination, and the Birth of a World) 0-312-42261-X.

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