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Ancient shore lines on the Island of Lanai, Hawaii

Harold Thornton Stearns
Ancient shore lines on the Island of Lanai, Hawaii
Bulletin of the Geological Society of America (April 1938) 49 (4): 615-628


The highest fossiliferous marine deposits yet found in the Hawaiian Islands lie on Lanai, at an altitude of 1069 feet. Stripping of the soil above this level indicates that the island may have emerged as much as 1200 feet. The fact that 10 to 50 feet of lateritic soil formed prior to this submergence and only a few inches have formed since proves that the period of time before this submergence was vastly greater than the time that has elapsed since. A prominent shore line is found also at the 560-foot level, and suggestions of intermediate ones are noted between it and the 1070-foot level. In the gulches, high marine deposits, not yet cut through by the present streams, indicate that the 560-foot shore line was not formed until after the present canyons were cut. Fossils show that this 560-foot submergence occurred in Pleistocene time. A sufficient number of marine deposits may be observed at altitudes between 250 and 270 feet to suggest strongly a halt of the sea between these levels, and numerous wave-cut platforms above it suggest other short halts as the sea receded from the 560-foot shore line. The next obvious shore line is at 100 feet, but it is probable that the submerged shelf 300 feet below sea level indicates a shore line that belongs chronologically between the 250-foot and the 100-foot strands. The sea then fell about 60 feet below its present level, and extensive dunes were formed. Next, the sea rose about 25 feet above its present level and finally receded to the point where it is now, with a short halt about 5 feet above the present level. Maunalei Gulch is now drowned at least 320 feet, and, although neither the position in the sequence nor the altitude of the shore line when this valley was cut is definitely known, this strand probably preceded the 1200-foot strand. At least, it preceded the 560-foot shore line, because the deposits of the sea that formed the 560-foot level partly fill the canyons of Lanai. Evidence is accumulating to show that all the large islands of Hawaii passed through the series of submergences and emergences recorded on Lanai. It is probable that after the 250-foot strand the sequence is the same for all the other islands and that the shore lines are concordant in height. Lanai was at one time submerged at least 1500 feet and probably considerably more. This amount appears too great to have been caused by changes in the level of the ocean due to changes in the volume of the polar ice caps; hence, it probably represents actual movement of the Hawaiian land mass. The later shore lines, however, may be eustatic. [The highest occurrence of coral on Lanai led Stearns to conclude that the island had to have been tectonically uplifted.]

ISSN: 1050-9747
Serial Title: Bulletin of the Geological Society of America
Serial Volume: 49
Serial Issue: 4
Title: Ancient shore lines on the Island of Lanai, Hawaii
Pages: 615-628
Published: 193804
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
Accession Number: 1939-018040
Categories: Invertebrate paleontology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: 3 pls., 1 fig. index map
N19°00'00" - N28°30'00", W179°00'00" - W155°00'00"
Source Note: abstract, Proc. 1936, p. 105, June 1937.
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from Bibliography and Index of North American Geology, U. S. Geological Survey, Reston, VA, United States. Reference includes data from U. S. Geological Survey, Hawaiian Volcano Observatory, , United States
Update Code: 1939
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