PHYTOGEOGRAPHY OF MANOA VALLEY, HAWAIIAN ISLANDS 565 
the mountain rampart falls, not upon the summit crest, but just to 
the leeward. The heads of the leeward valleys thus receive Oahu's 
maximum precipitation. The annual average for this is about 150 
inches, whereas the precipitation along the crest itself is about 100 
inches. Manoa is known locally as a very rainy valley. 
Rainfall has been a dominant factor in forming the valley and 
sculpturing its walls. At present it is the controlling factor in the 
distribution of the plant life of the valley. The following data, sup- 
< ^ 
Locality 
s 
a. 
>> 
c 
3 
a 
0 
< 
<; 
m 
0 
Q 
Annu; 
prox: 
Honolulu, on coastal plain, 
el. Ill ft 
18 
3 
7 
2 
2 
I 
I 
I 
2 
41 
Manoa, middle of valley, el. 300 ft. 
7 
7 
8 
8 
7 
6 
7 
8 
8 
7 
9 
9 
90 
Manoa, upper floor, el. 300 ft 
22 
3 
II 
9 
28 
12 
13 
19 
9 
9 
17 
24 
176 
Mount Tantalus, el. 1,360 ft 
8 
8 
9 
9 
8 
8 
9 
8 
9 
8 
II 
1 1 
106 
Fig. 2. / Contour Map of Manoa Valley 
I. Nuuanu Valley Gap; at the head of the valley, cutting completely through 
the Koolau Range. 
12. Ohu-ohi Amphitheater, on the windward side of the Koolau Range. 
13. Mount Olympus. 
14. Mount Kona-hua-nui, with two summit peaks. 
15. Mount Tantalus. 
16. Round top Hill; Sugar-Loaf lies directly mountainward, between the 
former and Tantalus. 
18. The Manoa-Palolo foothill. 
19. Apex of the Manoa-Palolo foothill. 
20. Transition region on the east lateral ridge. 
21. Mountainward portion of the east lateral ridge. 
22. Topographic transition region on the west lateral ridge. 
23. Mountainward portion of the west lateral ridge. 
24. Zone of precipices or palis that bound the upper valley head. 
25. Zone of the hanging valleys; in addition to the five or six large hanging 
valleys there are numberless small ones. 
26. Hanging valleys in the flanks of Mount Olympus, 
27. The lower valley floor. 
28. Manoa stream, crowded against the foot of the east ridge. 
29. The middle portion of the valley floor. 
30. Puu Pueo. 
31. The upper valley floor. 
32. 33, 34, 35. Talus zone and valley walls. 
36. Windward wall or precipice of the Koolau range. 
