VOLCANOES. 



705 



In true lava-cones, like Mount Loa, the crater is generally a pit- 

 crater, — a great depressed area in the surface of the mountain, like a 



Fig. 1109. 



'aaawalc 



Map of part of Hawaii. 



pit or quarry-hole in a plain, as in the summit-crater of Mount Loa 

 and in Kilauea, the latter 4,000 feet ahove the sea. A larger bird's-eye 



Fig. 1110. 



Crater of Kilauea, in 1840 : a, large boiling lake of lava ; at o and near e, sulphur-banks ; r, an 

 adjoining small crater ; p, neck between Kilauea and the crater r. 



view of Kilauea (with an adjoining small crater, r) is shown in Fig. 

 1110, and a vertical transverse section of the same, more enlarged, in 

 Fig. 1111. The pits have precipitous walls of stratified rocks ; for 

 the lavas are in layers, and the layers are nearly horizontal. 



At Mount Loa, the summit-crater is 13,000 feet in its longer diameter, and 780 feet 

 deep. Kilauea is 16,000 feet in its greatest length, seven and one half miles in circuit, 

 nearly four square miles in area, and GOO feet deep. After its last great eruption, of 1840, 

 45 



