First Lessons in Geology

ISBN: 9781330101049 出版年：2016 页码：133 Alpheus Spring Packard Forgotten Books

Now if there has been a recent shower, and the stream is rather high and the water thick and turbid, should we take up a tumbler-full of the water and allow it to settle, we shall see that the coarser particles fall to the bottom first and form a layer or stratum of gravel; above it is next deposited a layer of sand, and finally when the water has become clear, all the sedi ment having fallen to the bottom, we shall find uppermost a stratum of very fine sand, so fine that we cannot easily distin guish the particles, and this is mud. The entire deposit is said to be, in geological language, a sedimentary deposit.