Terra Sirenum

A low area in Terra Sirenum is believed to have once held a lake that eventually drained through Ma'adim Vallis.

[5] Evidence of deposits of chloride based minerals in Terra Sirenum was discovered by the 2001 Mars Odyssey orbiter's Thermal Emission Imaging System in March 2008.

[8] Based on chloride deposits and hydrated phyllosilicates, Alfonso Davila and others believe there is an ancient lakebed in Terra Sirenum that had an area of 30,000 km2 and was 200 meters deep.

Later, erosion (perhaps wind which can't move large rocks) removed much of the surface layers, but left behind the more resistant deposits.

Other ways of making inverted relief might be lava flowing down a stream bed or materials being cemented by minerals dissolved in water.

Examples of inverted channels on Earth are found in the Cedar Mountain Formation near Green River, Utah.

Inverted relief in the shape of streams are further evidence of water flowing on the Martian surface in past times.

[10] Terra Sirenum is the location of many Martian gullies that may be due to recent flowing water.

The radial and concentric cracks visible here are common when forces penetrate a brittle layer, such as a rock thrown through a glass window.

Ice being less dense than rock, pushed upwards on the surface and generated these spider web-like patterns.

Researchers believe these magnetic stripes on Mars are evidence for a short, early period of plate tectonic activity.

MOLA map showing boundaries of Terra Sirenum and other regions
MOLA map showing boundaries of Terra Sirenum near the south pole and other regions
Gullies with remains of a former glacier in crater in Terra Sirenum, as seen by HiRISE under HiWish program.
Close view of possible pingo with scale, as seen by HiRISE under HiWish program
Close-up view of concentric crater fill in a crater located in the Phaethontis quadrangle , as seen by HiRISE under HiWish program.