Historic Littoral Cones in Hawaii 
James G. Moore and Wayne U. Ault 1 
ABSTRACT: Littoral cones are formed by steam explosions resulting when lava 
flows enter the sea. Of about 50 littoral cones on the shores of Mauna Loa and 
Kilauea on the island of Hawaii, three were formed in historic time: 1840, 1868, 
and 1919. Five new chemical analyses of the glassy ash of the cones and of the 
feeding lava show that there is no chemical interchange between molten lava and 
sea water during the brief period they are in contact. The littoral cone ash contains 
a lower Fe^Os / (Fe 2 Oa + FeO) ratio than does its feeding lava because drastic 
chilling reduces the amount of oxidation. 
A large volume of lava entering the sea (probably more than 50 million cubic 
yards) is required to produce a littoral cone. All the historic littoral cones were fed 
by aa flows. The turbulent character of these flows and the included cooler, solid 
material allows ingress of sea water to the interior of the flow where it vaporizes 
and explodes. The cooler, more brittle lava of the aa flows tend to fragment and 
shatter more readily upon contact with water than does lava of pahoehoe flows. 
Littoral cones are common features on the 
shores of the younger volcanoes of Hawaii 
(Wentworth and Macdonald, 1953:28). These 
cinder cones do not mark the site of a primary 
volcanic vent but rather are produced by the 
violent steam explosions which result when some 
lava flows enter the sea. Upon such occasions 
the contact of molten lava with sea water pro- 
duces great jets of steam hundreds of feet high. 
These blasts carry the chilled and shattered lava 
high into the air. If wind and topography per- 
mit, some of this material falls back on the land 
and builds up a cone. Most of the material falls 
into the sea and is removed by ocean currents. 
Because of their location on the sea coast, 
littoral cones are very transient features and are 
rapidly removed by the sea; consequently they 
are found only on the youngest active volcanoes. 
On the shores of Kilauea and Mauna Loa on the 
island of Hawaii there are approximately 50 
littoral cones. No cones are known on the other 
1 U.S. Geological Survey, Hawaiian Volcano Observ- 
atory, Hawaii, and Isotopes, Inc., Westwood, New 
Jersey. Manuscript received September 11, 1963. 
Publication authorized by the Director, U.S. Geo- 
logical Survey. 
three volcanoes (Mauna Kea, Kohala, and Hua- 
lalai ) of which the island is composed, nor have 
any littoral cones been mapped on any of the 
other Hawaiian Islands. 
In historic time, cones have been formed at 
only three localities ( Fig. 1 ) . These three cones 
are of particular interest because their age and 
conditions of formation are known and because 
the lava flows which fed them can be identified. 
The three historic littoral cone localities are: 
( 1 ) Sand Hills, produced by the 1840 Kilauea 
flow; (2) Puu Hou, produced by the 1868 
Mauna Loa flow; and (3) the cone produced by 
the 1919 Mauna Loa flow. 
1840 Cones 
The remnants of the littoral cones produced 
in 1840 are on the coast 5 miles northwest of 
Cape Kumukahi, the east cape of the island 
(Fig. 1). The largest remnant is called Sand 
Hill and has an altitude of 118 ft, as shown on 
the 1924 topographic sheet. Shortly after its 
formation it was more than 300 ft high, accord- 
ing to Coan (Brigham, 1909:52), but it has 
been largely removed by the erosive action of 
the sea. 
SMITHSONIAN 
INSTITUTION 
