OF THE HAWAIIAN ARCHIPELAGO 485 
further increased by the low specific heat of sand.”’ This is also 
true of the Hawaiian sand strands. There isa greater temperature 
range on the beach itself than in the protected zone lying immedi- 
ately behind the beach. However, the temperature range of the 
littoral is insignificant when contrasted with that of the mountains 
that ascend directly from the lowlands, and in many places directly 
from the littoral. The diurnal range in temperature increases as 
one ascends the mountain slopes, and this range reaches its maxi- ° 
mum on the high summits of Kea and Loa (nearly 14,000 ft.). 
Guppy (’03—’06) found the mean daily range of temperature on 
the summit of Loa, August, 1897, to be 30.6° F.; the lowest reading 
was 15°, the highest 61.2°. 
Although sand has low specific heat, the upper dry layer becomes 
excessively hot under a cloudless sky. Cockayne (’11) records 
surface temperatures of 120°-127° F.on the New Zealand strand; 
these figures are even higher than the generalization made by 
Guppy in the table given below. It should be noted, however, 
that the wet underlayers of sand absorb heat much more slowly. 
At the depth of a few inches below the surface the sand is always 
moist, so that the roots of sand-strand plants descend very quickly 
into relatively cool soil. 
Guppy (’03~’06) makes the following generalizations concern- 
ing beach temperatures, the data applying to ordinary beaches 
under an unclouded sky, in the hot season, during the early after- 
noon: 
Surface—half-inch deep Four inches deep 
0°-105° 
Temperate about 50°-55° lat. ae) 
Subtropical 80 235 105 —I10 80 
Tropical 270 =20 = =< II0 —120 85 
Olsson-Seffer (’09, pp. 88, 89) gives an extensive series of 
strand temperatures secured by him in various parts of the world. 
With reference to temperature, Hawaiian strand regions may 
be classified as follows: 
I. Warmer strands—leeward, facing SE., S., or SW. 
1. Typical leeward beaches: e. g., Mana, Barber’s Point, leeward 
Molokai, Lahaina, and Kawaihae. 
2. Slope approaches plane perpendicular to incident sunlight: 
flat beaches, like those of Midway, Laysan, leeward Kauai 
and Puna. 
