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
Lava Cast Forest 1942, the United States Forest Service designated 5,120 acres as part of the Lava Cast Forest Geological Area and were promoted as a tourist attraction. In 1963, scientists from NASA became interested in the lava fields because they had very little erosion and they suspected it might be what they would find on the surface of the Moon. From 1964 to 1966, at least 46 astronauts trained for lunar missions in the area. James B. Irwin delivered a rock from one of Oregon's lava flows to the lunar surface to commemorate NASA's experiences in central Oregon. Lava Cast Forest Lava