This looks so much like Earth. I see gravels like these in Duluth’s abundant creeks and rivers. Scientists are calling it the first evidence of streambed gravels on Mars. A fracture in an outcrop called “Link” shows rounded pieces of gravel eroding from a layer of white rock. Called a sedimentary conglomerate, the outcrop was formed by the deposition of water and is composed of many smaller rounded rocks cemented together. Water transport is the only process capable of making rounded gravels like these.
The name “Link” is derived from a rock formation in Canada’s Northwest Territories, where there’s also a lake with the same name. “Hottah”, named after another lake in the Northwest Territories, also bares similar sedimentary rocks.
“The shapes tell you they were transported and the sizes tell you they couldn’t be transported by wind. They were transported by water flow,” said Curiosity science co-investigator Rebecca Williams of the Planetary Science Institute in Tucson, Ariz.
OK, we all know by now that Mars once had flowing water, but there’s nothing like seeing the evidence come in piece by piece. We’re on a collective hunt that one day may take us to some steamy hot spring or even a river coursing through a deep underground cave.
“From the size of gravels it carried, we can interpret the water was moving about 3 feet per second, with a depth somewhere between ankle and hip deep,” said Curiosity science co-investigator William Dietrich of the University of California, Berkeley.
That sounds even more like a typical small stream or creek on Earth, making visualization of this ancient Martian waterway that much easier. The slabs of busted rock are tilted layers of ancient streambed that remind me a lot of a more recent concrete parking lot I watched an excavator dig up recently.
The rounded shapes indicate a lengthy transport from further up Gale Crater’s rim, most likely from where the larger channel called Peace Vallis (above) feeds into the alluvial fan. Curiosity is poised along the edge of that fan as it ambles toward Glenelg, an area where three terrains of scientific interest converge: light-colored bedrock, a region rich in small craters and pebbly ground similar to where Curiosity touched down. Read more details of the discovery HERE.