Department of Earth Sciences

The Cerberus Fossae are two parallel extensional faults that run almost 1000 kilometres across a young volcanic plain in the Elysium Planitia region. The two trenches run almost exactly parallel to one another and stretch from northwest to southeast. They are extremely steep-sided throughout and in some places cut almost vertically down through the layers of lava. This is an indication that the trenches are still very young, as over time erosion causes rock to break off from steep slopes and edges, so that the gradient of the slopes become increasingly shallow.

The few impact craters on the volcanic plain also indicate that the landscape here cannot be very old. The age of the lava flows can be determined quite by counting all of the craters and measuring their various diameters, and comparing this with other areas of Mars. This method of determining the age of geological surfaces can be applied to all bodies in the Solar System that have a solid surface. Scientists therefore assume that parts of this plain were flooded with low viscosity lava in the recent geological past, possibly even less than 100 million years ago. Lava also rose to the surface out of the Cerberus Fossae (and later presumably so did groundwater). This makes the near-Equator region of the Cerberus Fossae one of the youngest geological structures on Mars.

The Cerberus Fossae are tectonic features originating most likely from dilational faulting or from subsidence due to dike emplacement. Rounded collapse pits observed in the northern Cerberus Fossae indicate an early stage of graben subsidence, and are particularly evident in the northern part of the Cerberus Fossae. Besides, numerous volcanic dikes formed in the Martian past in the north-western volcanic region of Elysium, which is home to the 12.5 kilometre-high volcano Elysium Mons. Dike emplacement induces deformation and can lead to the formation of fissures and graben at the surface above the dike.

The outflow channel system Athabasca Valles, which rises in the Cerberus Fossae can bee seen to the west of the image shown here. Presumably, the Cerberus Fossae fissures have ruptured the Martian crust millions of years ago to a certain depth, to be able to discharge lava from a volcanic source as well as groundwater.

The dark material within the Cerberus Fossae and on the floor of the unnamed impact crater were carried here by winds and formed dunes made of dark sand. Dark dunes are very common on the surface of Mars and consist of old volcanic ash.