Translations:Adventist Youth Honors Answer Book/Nature/Geology/23/en
4. Take a picture or make a sketch of each of the following geological features:
a. A bed of sediment that is coarser at the bottom and finer toward the top (This is called normal graded bedding.)
The size of a particle that a stream can transport depends on the stream's speed as well as the size and density of the particle. In general, the faster the current, the larger the particle that can be transported. As a stream slows, it drops the largest particles first. As it slows more, it continues to drop finer and finer particles. When the current stops, all sediments are deposited. In the diagram note how the sediment at the top is much finer than the sediment at the bottom. This natural sorting mechanism occurs whenever sediments are deposited, and can be used to detect boundaries between sedimentation events. A normal graded sediment indicates that the sediment layer has not been overturned since it was deposited, while an inverted bed (finer particles at the bottom, larger ones on top) indicates that the sedimentation layer was overturned after its deposition.
