OF THE HAWAIIAN ISLANDS. 



355 



walls of some vast pit. On opposite sides of the valley there is very little to indicate that 

 they were ever nearer to each other than at present ; they are not always of the same height, 

 their spurs and side ravines are different, but the arrangement of lava beds and their dip is 

 essentially the same. 



In Nuuanu Valley at the head of the ancient bay, and along the base of all the ridges 

 towards the east, a coarse black gravel is found at various depths, owing to the irregular 

 surface of the ground, but apparently nearly on the same level, in layers of one or two feet 

 in thickness. This gravel seems to be comminuted pitchstone, and contains a very large 

 amount of iron. It is often used to cover road-beds, and when crushed by the unshod hoofs 

 of the horses, forms a coarse powder, and an electro-magnet drawn through it for ten inches 

 becomes charged with particles of iron. The wash of the hills and the tufa of the coast 

 craters is often directly superimposed upon this bed. Near the lower end of Nuuanu a 

 stream of dark compact basalt crops out in the bed of a river, exhibiting rude columnar 

 forms. 



Next to Nuuanu on the east is Pauoa, a small but very beautiful valley filled with rice- 

 fields, kalo-ponds, banana plantations, and the grass houses of the natives, and remarkable 

 as affording a pathway for horses to the summit of the mountain at its head, the valleys of 

 the Hawaiian Islands usually ending in an abrupt wall often inaccessible to man. East of 

 this, Manoa Valley forms a broad circular plain inclosed by high and steep walls. The soil 

 is deep and rich. The rock is usually a gray or red cellular basalt, which becomes quite 

 soft on decomposition, so that when wet it may be easily cut with a knife, though when dry 

 it is as hard as an ordinary unpressed brick. It retains the shape of its nearly spherical 

 cells through these changes which must take place several times each week, as the showers 

 and sunshine alternate with wonderful rapidity in these mountain recesses. In many places 

 large bubbles have been formed in ancient lava streams which now form caverns, sometimes 

 of considerable extent with rough sides and roof. These are often exposed by the breaking 

 off of the outer wall, and have for ages formed convenient receptacles for the dead. 



The spurs of the side ridges project towards the mouth of the valley usually, but in 

 several remarkable instances the direction is 

 reversed. During the rains, the circus at the 

 head of Manoa presents a hundred cascades whose 

 white threads may be seen several miles at sea. 

 The ascent to Konahuanui by the western ridge 

 of Manoa is not difficult, although beyond the 

 first few miles the pathway becomes narrow 

 in places, and the ridge almost knife-edged. Fi e- 7 - si*, mag. b itafc Vdhy. 



Swamps and pools are met with on the way, and the whole soil is wet, even to the summit, 

 where moss covers the trees, and is usual]}' saturated with water from the clouds that settle 

 upon the mountain. Two cracks or rents occur, neither of them of any great size, but 

 remarkable for their position. The}' are both about twenty feet wide, and nearly the same 

 depth, the bottom being filled with loose 

 earth and stones. The rock exposed by 

 these sections is the red-brown cellular 

 lava which crops out below, and the strata 

 are much confused as if different streams fig. 8. cracks in the Manda Ridge. 



