Geology of Mauna Kea

Author:

Stearns, Harold T.

Title:

Geology of Mauna Kea

Periodical:

Geology and ground-water resources of the island of Hawaii

Year:

1946

Pages:

p. 150-169

Subject:

Geology Mauna Kea Mauna Kea history

Summary:

Mauna Kea has been studied in regard to certain special features by several earlier investigators, but this is the first report of the geology of the entire mountain. The first recorded ascent of Mauna Kea was in 1823 by the Reverend Joseph Goodrich, who again climbed the mountain in 1832. Goodrich described what he termed "fragments of granite" embedded in lava, which probably were the inclusions of gabbro quite common in the later cones of Mauna Kea. James Macrae, botanist attached to the British warship Blonde, commanded by Lord Byron, climbed Mauna Kea in 1825, recording his observations in his diary. David Douglas, exploring botanist, climbed Mauna Kea in 1834 and shortly afterward met a tragic death in a wild bull pit on the eastern flank of the mountain. Charles Pickering and W. D. Brackenridge, of the United States Exploring Expedition under the command of Lieutenant Charles Wilkes, U.S.N., climbed Mauna Kea in 1841. All of these early explorers briefly describe some of the general volcanic features of the mountain, but none of them were trained geologists, and the accounts are too vague to furnish much geological information. C. E. Dutton was the first trained geologist to examine Mauna Kea. During 1882 he ascended the mountain from Humuula Saddle, and spent a few hours in the summit region. He noted the lighter color and lesser vesicularity of the lavas of the summit region as compared with many of those at lower altitudes, and recognized the work of frost and ice in splitting apart many of the exposed rocks. E. D. Baldwin, in 1889, also recorded the difference between the lavas of the summit region and those typical of the lower slopes. He described the mountain as covered mostly with aa flows and "sand" cones. Hitchcock climbed Mauna Kea in 1886, but his observations were not published until 1909. He cited erosional valleys about the base of Mauna Kea as evidence of its greater age as compared to Mauna Loa. Bombs from the summit cones containing cores of dunite ("solid olivine") were described. Daly climbed the southern slope of Mauna Kea in 1909, and was the first to recognize evidence of a former glacier. He also recognized the andesitic nature of the lavas of the upper part of the cone, and suggested that the mountain consists of basalt below an altitude of 3,500 meters, and of andesitic basalt and trachydolerite above that level. Bryan described the general features of the mountain, and concluded that because the numerous large gulches are restricted to the lower part of the mountain, volcanic activity must be survived longer on the upper slopes. In 1925 T. A. Jaggar visited the southern slope and summit region of Mauna Kea, confirming Daly's conclusion of the former presence of a glacier, and calling attention to the large alluvial fans at the southern base of the mountain. A more detailed description of the glaciation of Mauna Kea was published by Gregory and Wentworth in 1937, and in 1941 Wentworth and Powers described what they believed to be the deposits of four separate stages of glaciation. Two of these have been shown by recent work to be explosion deposits, and the third to consist of torrential fanglomerates probably deposited by floods released by volcanic melting of the icecap. Other related features also have been described by Wentworth and Powers. Contributions to the knowledge of the petrography of Mauna Kea have been made by Cohen, Merrill, Daly, Cross, and Washington. Sidney Powers mistakenly believed the lava flow which forms the Laupahoehoe peninsula issued from fissures near the mouth of the valley. Wentworth has described the pyroclastic rocks of Mauna Kea.

URL:

http://pubs.usgs.gov/misc/stearns/Hawaii.pdf

Collection:

Monographs