191 
THE WATER RESOURCES OF MOLOKAI. 
Under the above title Waldemar Lindgren offers a valuable 
illustrated contribution to economic literature of the Hawaiian 
Islands. 
After a general introduction devoted to the topography of the 
island an interesting description of the geology follows : 
Like the other islands of the Hawaiian group, Molokai is almost 
entirely of igneous origin. It is a volcanic cone built up in the 
middle of the ocean by a great number of superimposed basaltic 
flows. The island is, in fact, like Maui, formed by two volcanoes, 
and these two cones are separated by a low gap on which secular 
disintegration has reduced the basalt to a deep red soil. The west 
end forms one, separate and complete, though comparatively low 
cone. Partly obliterated craters are still visible near the sum- 
mit, between Mauna Loa, Kaana, and Amikopala. The cone is 
not very regular, and secondary centers of eruption were probably 
located near the southwest and northwest corners of the island. 
The steep pali running north from Mauna Loa to the coast indi- 
cates a dislocation along which the east side has dropped a few 
hundred feet. 
The main or eastern part of the island is not of so simple a 
structure. It represents one part, and probably the smaller part, 
of a large volcano, the northern part having dropped down along 
a great break or dislocation to a depth of from a few hundred to 
3.000 or even 4.000 feet. Thus, the great northern pali is really 
an immense break or a fault line, which split the volcano in two. 
The slopes of the lava flows are everywhere to the south from 
4" to 13 0 , even in the cliffs of the north coast the same inclina- 
tion is observed. This, in conjunction with the form of the 
island, shows that a part of the volcano has been removed. 
Neither wave action nor erosion by running water could possibly 
have produced such an escarpment as that of the great pali, reach- 
ing 3.000 feet in height. The work of erosion on this cliff is 
shown plainly enough in the great alcoves cut by the water 
courses. This erosion is still cutting southward and the divide is 
no doubt steadily migrating in that direction. 
A coral reef from one-half to one mile fringes practically the 
whole southern coast of the island. The parts adjacent to the 
main gulches are gradually being filled up bv mud. Thus, the 
island is gradually growing out in this direction. Seen from a 
high point, the reddish mud flats skirting the shore contrast 
strongly against the brilliant emerald green of the reef ; and be- 
yond this is the dark violet-blue color of the deep sea. Small 
amounts of coral rock, indicating a former higher water level, are 
