Friday Headlines, January 9, 2015
THE LATEST IN THE GEOSCIENCES
Life on Mars?
Mammoth-killing impact? Probably not.
Images of sedimentary rocks (those rocks formed from when particles of other rocks are eroded, transported, and deposited then later transformed to rock) from Mars show structures that we know are related to the actions of water. Streams and lakes apparently existed on Mars in the remote past.
With the presence of liquid water on Mars, at least in the past, it makes sense that life too might have existed, or may yet still exist in some hidden place. However, no direct evidence of life has been found.
Recently, the Curiosity Rover took photos of a sandstone (referred to as the Gillespie Lake sandstone) which appears to represent a lake environment. More importantly, the surface of this sandstone bears features that on Earth would be interpreted as microbial mats, or thin films of bacteria and single-celled organisms that covered the sea floor and still form a layer on the bottom of standing bodies of water.
This is the first potential fossil evidence of life on Mars.
It’s still possible that these structures are mis-interpreted – there’s only so much one can do with a photograph – but it’s pretty compelling. If they are fossil organisms, they may lend great insight to the history of life on Earth, but are no guarantee that life still exists on Mars.
It has been put forward that the extinction of the so-called ‘megafauna’ (mammoths, mastodons, woolly rhinos, giant sloths, saber-toothed tigers etc) was caused not by the influence of man, nor by the influence of climate change at the end of the last glacial event, but instead was caused by a meteor impact around 12,900 years ago. One line of evidence for a meteorite impact is tiny glassy droplets of scoria, something that can only form from intense heat and melting of sediments, which could occur with an impact event.
Four archaeological sites in Syria that have these droplets of scoria and are of approximately the correct age were examined for evidence of an impact source. The study shows that the droplets are not related to an extraterrestrial impact, but instead to the burning of the simple homes in which people lived which were made of local mud and straw.