- journal_title：Geological Society of America Bulletin
- Contributor：W. N. HOLLAND ; G. PICKUP
- Publisher：Geological Society of America
- Date：1976-
- Format：text/html
- Language：en
- Identifier：10.1130/0016-7606(1976)87<76:FSOKDI>2.0.CO;2
- journal_abbrev：Geological Society of America Bulletin
- issn：0016-7606
- volume：87
- issue：1
- firstpage：76
In a flume study of knickpoint development in stratified sediment, two thin sand beds were intercalated between beds of cohesive material. The sand beds acted as knickpoint-forming horizons on which stepped knickpoints were developed and maintained as they moved upstream, creating an apparently stable form consisting of a channel-in-channel system. The system had four basic elements: (1) an aggraded reach upstream of the knickpoint, terminating on the downstream end at a fill-incision transition zone; (2) an oversteepened reach just above the knickpoint face; (3) the knickpoint face; and (4) an incising reach, often covered by moving sediment between successive knickpoints.
Apparently the presence of a knickpoint-forming horizon reduces knickpoint retreat rates, which were much lower in this study than those observed in an experiment with cohesive material but no intercalated sand beds and a similar discharge. Also, the channel-in-channel system that results from stratification is apparently fairly insensitive to the effects of changing discharge.