Hesperian

The Hesperian is a major geologic system and time period on Mars. During this time, Mars had a lot of volcanic activity and big floods. These floods made huge outflow channels on the planet's surface. The Hesperian shows the change from the wetter Noachian period to the dry, cold Mars we see today.

This period started after the Late Heavy Bombardment, about 3700 million years ago. It probably ended between 3200 and 2000 million years ago. When big impacts stopped, volcanism became the main thing happening. It made big flat areas of flood basalts and helped form large shield volcanoes like Olympus Mons.

Volcanic activity let out gases like sulfur dioxide (SO₂) and hydrogen sulfide (H₂S). These changed how water shaped the planet's surface. Later, as Mars cooled and its air thinned, deep groundwater sometimes burst through frozen ground. This made huge floods that carved wide channels and may have made big lakes or an ocean in the north.

Description and name origin

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

Hesperian chronology and stratigraphy

Martian time periods are based on looking at the planet's surface from space images. Scientists study areas with different looks to learn about Mars' 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 learn the age of different surface areas on Mars.

Mars during the Hesperian Period

The Hesperian was a time when Mars had less frequent space impacts, 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 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 has notes and sources that help prove the facts in the article. It talks about the Hesperian time on Mars. To read more, look at 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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