Horizontal and Vertical Stratification
3.2, 3.2.2 Stratification in Alluvium. These pictures were taken in stream beds in Palo Duro Canyon, Texas.
Horizontal stratification Notice the change in particle size across the channel.  The largest particles are deposited in the zone of greatest flow.  Finer particles are deposited by slower- moving water.
horizontal stratification in creek channel horizontal stratification in creek channel
Vertical stratification This looks at a vertical cross-section of the soil.  If there are layers of different texture above and/or below, vertical stratification exists.
vertical stratification in creek bank vertical stratification in creek bank
These are three views of the same bank, zooming in from above to right.
 

There is a layer of gravel and coarse particles near the top of the haft.
 

The texture is finer near the bottom of the haft, and there is an accumulation of slightly decomposed organic residues.

This type of stratification is typical of a stream bank, and of many alluvial soils.  Many of these layers may have been deposited by the same flood event, since the water does not flow at constant velocity during a flood.

The subgroup classification, fluvial, is used in Soil Taxonomy to describe these soils.

 vertical stratification in creek bank

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