blog.Jelmer Oosthoek.nl

Mars revealed
Mars is in the news a lot these days, with stories about a wet Mars in the past. Beautiful images are being sent from Mars orbit satellites to Earth every day and even the subsurface isn’t safe anymore with ground penetrating radars imaging subsurface layering in the Mars polar deposits.

So what’s on Mars?
All this data shows that Mars was more wet billions of years ago: during the Noachian epoch and later on occasionally during the Hesperian epoch. Ancient river systems can be seen in images, even deltaic deposits like the Mississippi delta. Catastrophic floods ripped through the terrain forming enormous channels, kilometers deep. Also enormous volcanoes can be seen on the surface of Mars. Olympus Mons for example is 27 kms high and 550 km in diameter.

Enormous systems of dikes (an intrusive igneous body) occur on Mars, called dike swarms. Most dike swarms on Mars are associated with the Tharsis region, an enormous volcanic plateau which consists of almost all major volcanoes on Mars, including the aforementioned Olympus Mons.

Millions of impact craters cover the surface of Mars. The Hellas Basin, for example, is 2300 km in diameter. The Northern hemisphere of Mars is lower in elevation then the Southern hemisphere and could very well also have been formed by major impacts.

Back to Earth
Was Earth geological history fairly uniform or did it also see catastrophic events? Well, catastrophic events did occur but it is not clear how big their influence was on the geological evolution of Earth. Major volcanic provinces can be found for example, such as the Deccan Traps and the Siberian Traps. The latter are around 1000 km in diameter. Dike swarms also occur on Earth. A major example is the Mackenzie dike swarm which is 500 by 3000 km in size.

Catastrophic floods have also occurred on Earth, mostly ice-age related. The best known example, which acted as analog for the Martian catastrophic flood morphology, are the Missoula Floods which formed the Channeled Scabland of the Columbia Plateau in Washington State, USA. It is attributed to the breaking of an ice-dam. Another example has been observed using bathymetry data from the floor of the English Channel between the UK and France. Streamlined islands and longitudinal erosional grooves can be observed which are attributed to “large-scale subaerial erosion by high-magnitude water discharges”. Interesting what the Bathymetry of other straits like Gibraltar and the Bosporus will reveal…

Enormous impact craters must also have wrecked havoc on Earth. The best evidence for that is of course the Moon itself. It is believed to have been formed due to an impact of a Mars sized object into the Earth, around 4.5 billion years ago. This swept a large part of the object and the Earth crust into orbit which accreted to form the Moon. Also the surface of the Moon is littered with impact craters. The largest impact crater on the Moon is the South Pole-Aitken basin, which is 2500 km in diameter. On Earth geological processes cleaned the surface and removed major structures like impact craters. But perhaps remnant imprints can still be observed in gravity and topography data?