Eos Chaos may be made of layer after layer of lava flows, probably mixed with deposits of volcanic ash that fell out of the air following big eruptions. It is likely the rock strata in the walls preserve a long geological history of Mars. Dark layers may be due to dark lava flows. The dark volcanic rock basalt is common on Mars. However, light-toned deposits may have resulted from rivers, lakes, volcanic ash, or wind blown deposits of sand or dust. The Mars Rovers found light-toned rocks to contain sulfates. Probably having been formed in water, sulfate deposits are of great interest
Cinder Cone and the Fantastic Lava Beds Snag Lake on the south and then Butte Lake to the north. Butte Lake is fed by water from Snag Lake seeping through the lava beds. Nobles Emigrant Trail goes around Snag Lake and follows the edge of the lava beds. Its age has been controversial since the 1870s, when many people thought it was only a few decades old. Later, the cone and associated lava flows were thought to have formed about 1700 or during a 300-year- long series of eruptions ending in 1851. Recent studies by U.S. Geological Survey (USGS) scientists, working in cooperation with the National Park