32 J. D. Dana — History of the Changes in Kilauea. 



The projectile process in the basalt- volcano, as long as it is in 

 its normal stage, makes not cinder-cones, but dribblet-cones, 15 

 to 40 feet high, out of the projected masses, the falling driblets 

 becoming plastered together about the smaller places of ejec- 

 tion. Such cones consist of cohering drops, clots, pancake-like 

 patches, or abortive streamlets, and form into spires and col- 

 umns on rude bases and take other fantastic shapes. They are 

 necessarily small, and mostly of blow-hole origin, because when 

 the vent is broad, like a lava-lake, the jettings fall back into it 

 again ; yet enough may fall on the margin of a lava-lake to 

 gradually raise and steepen its border. Such driblet-cones are 

 of all angles from 30° to 90°. Among the projectile results of 

 volcanoes, driblet-cones are at one extremity of a series, and 

 cinder or tufa cones, many hundreds of feet high, at the 

 other. A cinder cone of 1000 feet in height has 15,000 to 

 20,000 times the bulk of any driblet-cone. The process is 

 one ; but the result varies with the mobility and fusibility of 

 the lavas. 



Further : in the great lava cone of a basalt-volcano in its nor- 

 mal stage, cinder or tufa deposits rarely alternate with the large 

 lava-streams, while they commonly alternate in other kinds of 

 volcanoes. 



Further: cinder cones and beds of volcanic ashes may form 

 about a basal t-vocano, as already explained, whenever the con- 

 dition of insufficient heat is in any way occasioned. 



The above views as to the characteristics of a normal basalt- 

 volcano are sustained by the facts from the volcanic mountains 

 of all the Hawaiian Islands. 



In the first place, the slopes are not only the lowest possible, 

 usually from 1° to 10°, but continuous flows of 10° to 90° 

 occur. I have seen many of them descending as unbroken 

 streams vertical precipices on southern and western Hawaii. 



Again the alternation of the lava-streams of the great volca- 

 noes with deposits of volcanic sand, scoria or stones that were 

 ejected from the great craters, is of rare occurrence, and such 

 deposits make only thin beds of the kind whenever they occur. 

 In such examinations as I have been able to make of the walls' 

 of Kilauea and Haleakala, and of the precipices and bluffs of 

 Oahu, 1 have not succeeded in finding cinder or tufa deposits 

 among the layers. The walls of Kilauea are stratified from top 

 to bottom, but with lava-streams, and comparatively thin 

 streams ; I could find no evidence, in my examination of its 

 walls, of any intervening stratum or bed of scoria, tufa or 

 stones like that which now covers its border. This testimony 

 is not conclusive as to the absence of such projectile eruptions 

 in former times, for thin beds of scoria or sand like that just re- 

 ferred to — its thickness is only 25 to 30 feet — might be fused 



