Skip to Main Content
Skip Nav Destination
GEOREF RECORD

When knickzones limit upstream transmission of base-level fall; an example from Kaua'i, Hawai'i

L. Wren Raming and Kelin X. Whipple
When knickzones limit upstream transmission of base-level fall; an example from Kaua'i, Hawai'i
Geology (Boulder) (October 2022) 50 (12): 1382-1386

Abstract

A threshold drainage area limits fluvial transmission of base-level fall and may be expressed in the form of a waterfall or a series of waterfalls, defined here as a knickzone. Knickzones on the west coast of Kaua'i, Hawai'i (USA), exhibit evidence of a threshold drainage area. Eighteen (18) of the 25 knickzones in our study area are located at the coast or a tributary junction, have a drainage area <1.5 km (super 2) , and have been stationary for at least 1.5 m.y. The other seven knickzones are located >1 km upstream from the coast or nearest tributary junction and range in drainage area from 1 to 5.5 km (super 2) . Both sets of knickzones limit incision relative to canyons without knickzones. Field observations show strong 'a'a flows and dikes always crop out at the lip of knickzones, suggesting these resistant rocks and coarse sediment generated from them act to inhibit knickzone migration. A model incorporating flood records and channel conditions above knickzones shows thresholds of coarse sediment entrainment are never exceeded below 1 km (super 2) . Our results demonstrate knickzones on the west coast of Kaua'i are enduring features explained by resistant lava flows and physical limits in bedrock incision.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 50
Serial Issue: 12
Title: When knickzones limit upstream transmission of base-level fall; an example from Kaua'i, Hawai'i
Affiliation: Arizona State University, School of Earth and Space Exploration, Tempe, AZ, United States
Pages: 1382-1386
Published: 20221011
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 33
Accession Number: 2022-064341
Categories: Igneous and metamorphic petrologyGeomorphology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
N21°45'00" - N22°15'00", W160°15'00" - W159°19'60"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 202248
Close Modal

or Create an Account

Close Modal
Close Modal