Streams which flow for only a part of the year are ________.
A hot spring that water is known as a ________.
Caves are found in most parts of the world where there are thick ________ deposits under the surface.
At its maximum extent, ice covered almost ________ of the Earth's land surface.
Hills rounded and sheared off by glacial erosion are called ________.
The maximum extent of a glacier is marked by a ________.
A huge boulder resting on a completely different type of bedrock in glacial zones is a(n) ________.
The largest scale among the following representative fractions is ________.
The main component of the lower atmosphere by total volume is ________.