erosion
December 26, 2016
A Piece of Mars: Nicholas Steno was a 19th century geologist, who came up with some principles that are still used today to guide interpretation of exposed sedimentary rocks. The principles seem a bit obvious, but then some of the […]
December 12, 2016
A Piece of Mars: Higher ground is to the left. You’re seeing a tan layer sandwiched between two gray layers in this 0.96×0.54 km (0.6×0.34 mi) scene. Large ripples have accumulated in the lowest area to the right, which is […]
October 31, 2016
A Piece of Mars: This 1.6×2 km (1×1.24 mi) scene mostly shows what wind will do to fine-grained, weakly-consolidated surfaces. It has created topography that further strengthens wind scour in the hollows, which even leave kilometers-long grooves reminiscent of water-carved […]
October 10, 2016
A Piece of Mars: OK, you have to bring out the red/blue glasses for this one. (Or click here if you’re missing your glasses and want the black and white version.) Eberswalde crater has some lovely layered deposits, long ago […]
October 3, 2016
A Piece of Mars: HiRISE is celebrating 10 years of success by showcasing its first high resolution image, taken back in 2006. Here is a portion of it, shown at 1/4 the full resolution (the scene is 2.5×2.5 km across). […]
September 19, 2016
A Piece of Mars: This 0.96×0.54 km (0.6×0.34 mi) late winter scene is a study in contrast. The dark top half is uniformly rippled. This is the shady surface of the main windward side of one of Mars’ biggest dunes, […]
September 5, 2016
A Piece of Mars: Barchan dunes on Mars have a characteristic crescent shape, with a steep slope (“slip face”) on the inside of the sharpest curve (see examples like this, this, these, or this). This image (873×491 m, or 0.54×0.31 […]
August 29, 2016
A Piece of Mars: How far do windblown materials move on Mars? This scene (0.9×1.2 km, 0.56×0.75 mi) shows a bright layer of bedrock (top right) that is eroding, exposing a darker, bluish rock (bottom left). Ripples 5-20 m wide […]
August 22, 2016
A Piece of Mars: The erosionally-streamlined bright areas are on high ground. They are remnants of a vast dusty mantle that once covered this whole area – the rest of it has been blown away. The surrounding regions (check out […]
August 15, 2016
A Piece of Mars: Potential signs of wind activity are everywhere on Mars. Take this 0.96×0.54 km (0.6×0.34 mi) scene, which is on bedrock dated to be several billion years old. There’s a fabric of ridges trending from the upper […]
August 8, 2016
A Piece of Mars: This 1.92×1.08 km (1.19x 0.67 mi) scene shows eroded ridges that are, in fact, lithified dunes. They are so old that you might not recognize them as dunes without more context. This doesn’t happen much on […]
July 25, 2016
A Piece of Mars: Just like at Earth’s Grand Canyon, erosion on Mars has created some really beautiful landscapes. This 480×270 m (0.3×0.17 mi) scene shows rugged terrain that was once buried in sediment. Does the texture here represent the […]