Athabasca Valles
Encyclopedia
Athabasca Valles is an outflow channel on Mars
, cut into its surface by catastrophic flood
ing. It is one of the youngest known of these structures, probably forming only in the geologically recent past of Mars. The flood produced distinctive "teardrop" landforms similar to those found in the channeled scabland region of the United States
on Earth
. It is thought that these landforms were produced though depositional processes wherein the floodwaters dropped sediment behind resistant bedrock outcroppings and craters. The source of water for the flood is thought to be Cerberus Fossae
, at 10 N and 157 E. Groundwater may have been trapped under a cryosphere which was broken when the fossae was created.
The very high spatial resolution images from the HiRISE camera on board the Mars Reconnaissance Orbiter have revealed that all the flood features are draped by lava flows (Jaeger et al., 2007).
Research, published in January 2010, described the discovery of a vast single lava flow, the size of the state of Oregon
, that "was put in place turbulently over the span of several weeks at most." This flow, near Athabasca Valles, is the youngest lava flow on Mars. It is thought to be of Late Amazonian Age.
The floor of Athabasca Valles is peppered with thousands of small cones and rings formed as steam exploded through the lava flow. Because the flood-carved surface is now covered by lava, it is no longer easy to determine the age of the water floods that passed through Athabasca Valles. It is plausible that the flood was triggered by rising magma and hence the water flood and lava flows are essentially contemporaneous, but this has not been confirmed.
Around 80% of the craters in Athabasca Valles are secondary crater
s from the impact that created Zunil crater
.
Images from HiRISE in the Athabasca Valles region show features formed by the expansion and contraction of ice. Because these features occur in a channel that was active only 2 million years ago, the features hint at a warmer climate existing later than generally thought. To make the features, ice melted to form liquid water, then refroze. The detailed images from HiRISE show features similar to common landforms on Earth where permafrost is melting (polygonally patterned surfaces, branched channels, blocky debris and mound/cone structures).
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
, cut into its surface by catastrophic flood
Flood
A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...
ing. It is one of the youngest known of these structures, probably forming only in the geologically recent past of Mars. The flood produced distinctive "teardrop" landforms similar to those found in the channeled scabland region of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
on Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
. It is thought that these landforms were produced though depositional processes wherein the floodwaters dropped sediment behind resistant bedrock outcroppings and craters. The source of water for the flood is thought to be Cerberus Fossae
Cerberus Fossae
The Cerberus Fossae are a series of semi-parallel fissures on Mars formed by faults which pulled the crust apart in the Cerberus region . Ripples seen at the bottom of the fault are sand blown by the wind ....
, at 10 N and 157 E. Groundwater may have been trapped under a cryosphere which was broken when the fossae was created.
The very high spatial resolution images from the HiRISE camera on board the Mars Reconnaissance Orbiter have revealed that all the flood features are draped by lava flows (Jaeger et al., 2007).
Research, published in January 2010, described the discovery of a vast single lava flow, the size of the state of Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
, that "was put in place turbulently over the span of several weeks at most." This flow, near Athabasca Valles, is the youngest lava flow on Mars. It is thought to be of Late Amazonian Age.
The floor of Athabasca Valles is peppered with thousands of small cones and rings formed as steam exploded through the lava flow. Because the flood-carved surface is now covered by lava, it is no longer easy to determine the age of the water floods that passed through Athabasca Valles. It is plausible that the flood was triggered by rising magma and hence the water flood and lava flows are essentially contemporaneous, but this has not been confirmed.
Around 80% of the craters in Athabasca Valles are secondary crater
Secondary crater
Secondary craters are impact craters formed by the ejecta that was thrown out of a larger crater. They sometimes form radial crater chains.-External links:*...
s from the impact that created Zunil crater
Zunil (crater)
Zunil is an impact crater near the Cerberus Fossae on Mars, with a diameter of . It is named after a town in Guatemala. Visible in images from the Viking 1 and Viking 2 Mars orbiters in the 1970s, Zunil was subsequently imaged at higher resolution for the first time by the Mars Global Surveyor ...
.
Images from HiRISE in the Athabasca Valles region show features formed by the expansion and contraction of ice. Because these features occur in a channel that was active only 2 million years ago, the features hint at a warmer climate existing later than generally thought. To make the features, ice melted to form liquid water, then refroze. The detailed images from HiRISE show features similar to common landforms on Earth where permafrost is melting (polygonally patterned surfaces, branched channels, blocky debris and mound/cone structures).