Lesson Summary
- Rivers and streams erode the land as they move from higher elevations to the sea.
- Eroded materials can be carried in a river as dissolved load, suspended load or bed
load. - A river will deeply erode the land when it is far from its base level, the elevation where
it enters standing water like the ocean. - As a river develops bends, called meanders, it forms a broad, flat area known as a
floodplain. - At the end of a stream, a delta or an alluvial fan might form where the river drops off
much of the load of sediments it carries. - Caves form underground as groundwater gradually dissolves away rock.
Review Questions
- What are the three kinds of load that make up the particles a stream carries. Name
and define each type. - What is a stream’s gradient? What effect does it have on the work of a stream?
- Describe several erosional areas produced by streams. Explain why erosion occurs here.
- What type of gradient or slope would a river have when it is actively eroding its stream
bed? Explain. - When would a river form an alluvial fan and when will it form a delta? Describe the
characteristics of each type of deposit. - What are two formations that form inside caves?
- What erosional feature formed by groundwater could swallow up your house?
Vocabulary
alluvial fan Curved top, fan shaped deposit of coarse sediments that forms when a stream
suddenly meets flat ground.
base level The elevation at which a river meets standing water; a stream cannot erode
below this level.
bed load The largest particles moved by streams; move by rolling or bumping along the
stream bed.
competence A measure of the largest particle a stream can carry.
delta A flat topped, triangular shaped deposit of sediments that forms where a river meets
standing water.