Friday Headlines, November 15, 2013
THE LATEST IN THE GEOSCIENCES
Physical evidence of bacterial activity from 3.5 billion years ago
Fossilized insects doing what?
Lava that keeps flowing and flowing and flowing
Paleontologists usually look for and study body fossils – the remains of the actual bodies of dead organisms, like shells or skeletons – in their quest to better understand life in Earth’s remote past. But not all evidence comes from body fossils.
Another important source of information about past life is the study of tracks and traces. Tracks are the footprints or other marks left by an organism as it moves by. Traces are incidental marks left by an organism while it was doing something else. Organisms may leave characteristic marks in sediments while feeding, or its tail may drag while it walks by.
Some organisms affect the shape of the surface upon which they live. Even microorganisms like bacteria. They make lovely mats that completely coat and smooth the surface. These are called microbially induced sedimentary structures, or MISS. These mats can be fossilized. And that’s what scientists recently described from the Pilbara Region of Western Australia.
What’s especially cool about these rocks, from the Dresser Formation, is that they are about 3.5 billion years old. The implication is that life on Earth existed at that remote age (and had to then appear at an even older age).
We do already have some evidence of life predating these sediments, but it’s mostly geochemical. These rocks represent the oldest physical evidence of life on Earth.
Well, it was bound to happen. For billions of years, life on this planet has succeeded in reproducing itself, and for hundreds of millions of years, one of the dominant forms of life have been the insects. At some point, these animals had to have been caught and fossilized in the act of doing it. You know. It. Mating.
The finding of these fossil froghoppers shows that over the last 165 million years the genital shape and mating position for froghoppers hasn’t changed!
Lava and lava floes come in many varieties. Some are very runny, almost water-like. Others are clumpy and explosive. Most, despite their extreme temperatures, only flow for a few days then solidify.
There are however, some flows that may take almost a year to cool and solidify.
The Puyehue-Cordón Caulle volcano in Chile last erupted in April of 2012, resulting in flows of obsidian lava.
Obsidian is volcanic glass, which is commonly used to make arrowheads and can be used to make some of the sharpest blades known to man.
In January of 2013, scientists visiting the volcano were shocked to find that the lava was still flowing. A cooled, outer crust of black rock shields the lava that still flows within, keeping it warm enough to remain molten at temperatures up to 900°C.