What describes a lava flow that travels downhill at over 100 mph ?!

The creation of the trans-siberian railway allowed people to travel across russia. how could this railway impact russian culture?

If we review the changes in the landscape surrounding the great salt lake in utah we can see a change in topography. look at the area to the south of the lake. what change has occurred during the last twenty-nine years? a) erosion of the hills b) an increase in marshland c) flooding of the area and the development of wetlands d) deposition of sediments and an increase in elevation

What is the border between layers a through f and layer g called?