Kilanra and Manna Loa. 





^M^'-^.^:i 



objurgations of an English geologist, it has been adopted by all geologists treating of 

 the Hawaiian lavas. Another native word, a-a, supplies another want, for nowhere in the 

 English language is there a word expressive of the roughness of the rock mass to which 

 this word is applied ( PL XLVII); a third, //;;/«, meaning moss or seaweed, is well applied 

 to the basaltic pumice which accompanies all the Hawaiian ott/bnrs/s of lava (Fig. 2). 

 Now the rough scoriae, a-a and limu, 

 quickly invite vegetation when 

 moisture is present, and do their 

 best to cover the ravages of Pluto 

 with the garments of Ceres, but the 

 smooth lava does no such good work, 

 although pleasanter to walk upon ; 

 only when its great slabs, smooth or 

 slightly wrinkled in the cooling pro- 

 cess, are cracked, can the vegetable 

 get a footing. We will retiirn to the 

 forms and nature of the lava later 

 with such help as flat pictures can 

 give the reader. 



While rivers of water irrigate 

 and support the vegetation in the 

 lower valle3\s, the}-, in bringing down 

 soil, of course erode the hills and cut 

 the valleys deeper; a process Dana 

 has well illustrated from the erosion 

 of one of the Pacific islands. The 

 rivers of stone build up and often 

 where the river has cut a channel on 



this island, as in the case of the Wailuku at Hilo, we see a contest between the destruAion 

 and the renewal. Within historical times the river has more than once been wiped out 

 by the fiery flood, and has patiently set to its work of cutting a new channel (Fig. 3). 



It is easy to see that the constant outpour of lava from a group of volcanic vents 

 would not only increase the height of an island but its circumference as well in an 

 even proportion were there not some check to the latter increase. The check in the 

 present case is the erosive power of the sea currents and waves. Hawaii is not pro- 

 tected by a fringing coral reef, for owing to the frequent submarine eruptions as well 

 as to the flows that rush down the mountain sides and push out the shore line, the 



Fig. I. OLD FLOW WKST OF KILAUEA. 



