OF THE HAWAIIAN ARCHIPELAGO : 495 
logical history of the islands the Hawaiian strand was wholly of 
sheet lava, and today remnants of this primitive beach condition 
exist here and there along the coasts. Thus there is great diversity 
in the ages of the various shores, and in the amount of plant in- 
vasion, both from within and from without, to which they have 
been exposed. 
2. Vertical rock shores or sea cliffs—These are composed 
either of sheet lava or laminated tufa. They are produced by sea 
action and fracture. Some of the stupendous sea-clifis of Hawaii, — 
Molokai, and Kauai, may have been produced by volcanic or 
seismic activity. The sea-cliffs either rise sheer from the water, 
or have a narrow strand at the base; this depends upon the depth. 
of the off-shore water and both conditions are of frequent occur- 
rence. None of the sea-cliffs, no matter how precipitious or ap- 
parently uncongenial for plant life, are wholly devoid of vegetation. 
Here and there on the surface of the cliff are crevices, ledges, and 
little pockets where plants establish themselves. 
On the arid precipices—e. g., Koko Head, Makapuu, Mokapu 
and Kaena—occur such plants as Euphorbia cordaia, Lepidium 
owathense, Schiedea globosa, Kadua littoralis, Tetramolopium spp., 
Lipochaeta integrifolia, Gossypium tomentosum, Sida spp., Jac- 
quemontia sandwicensis, Boerhaavia diffusa, Cassia Gaudichaudit 
and Capparis sandwichiana. 
On the humid sea-cliffs—e. g., Waipio, Nahiku and East Mo- 
lokai—are such forms as Campylotheca molokaiensis, Schiedea 
Lydgatei, Lysimachia spathulata, Metrosideros polymorpha, Tri- 
bulus cistoides and Nama sandwicensis. 
3. Littoral creviced rocks.—Along the lava flow and tufa-cliff 
coasts, and to a lesser degree along the uplifted coral limestone 
shores, the rock crevices are the special habitats of many strand 
plants. The crevices are of two kinds: those due to the lamina- 
tion of the rock, that is of the sheets or layers of lava or tufa; and 
those due to the vertical faulting of these layers. . The former con- 
dition produces horizontal crevices, which on the sea-cliffs often 
front on ledges of greater or less magnitude. The vertical check- 
ing and faulting produces numberless irregular crevices upon the 
surface of the exposed strata, and in these crannies soil, seeds, and 
spores are lodged. Many of the crevices are less than an inch in 
