A. B. Lyons — Composition of Hawaiian Soils. 425 



recent eruption of an extinct volcano, whose older lavas are 

 distinctly less basic. The volcano must have been for many 

 ages wholly extinct previous, to the period of activity during 

 which this black sand was ejected, in a stupendous explosive 

 eruption, which spread it over an area many square miles in 

 extent, in a stratum from one to fifty meters or more in depth. 



The points of interest in the composition of this lava are its 

 low content of silica and the very large proportion it contains 

 of ferrous iron, of unoxidized sulphur and of phosphoric acid. 



No. 2 is lava from a cinder cone at the base of the volcano 

 from which the black sand was ejected. The black sand over- 

 lies this lava at some points, but I believe that they belong to 

 the same period of volcanic activity, so recent that even in 

 exposed situations the wrinkles and creases, formed while the 

 lava was in a pasty condition as it cooled, remain as sharply 

 defined as ever. The chemical composition agrees in the main 

 with that of No. 1, the differences being, in part, what we 

 might expect from differences in the circumstances of the 

 respective eruptions. Unoxidized sulphur has nearly disap- 

 peared, and the proportion of ferrous iron has been greatly 

 reduced, by prolonged exposure of the fluid lava to the air. 

 There are, however, interesting differences in the original com- 

 position of these two products of a single volcano, the expla- 

 nation of which is beyond the scope of the present paper. 



The presence in notable quantity of cobalt, and the extra- 

 ordinarily large proportion of manganese and of phosphoric 

 acid are the points of especial interest. Lavas from Telegraph 

 Hill, three miles distant, nearly or quite as recent, exhibit the 

 same peculiarities in chemical composition. In both localities, 

 incrustations of manganese dioxide occur on rocks that have 

 been submerged. 



In No. 3 we have a lava of a totally different character. It 

 is a bluish gray, compact, minutely crystalline lava, contain- 

 ing much feldspar and very little chrysolite, and is the pre- 

 vailing rock in the Kohala mountain, at least in the Waimea 

 neighborhood. It seems to be similar to the lavas sent to 

 Prof. Dana by Kev. S. E. Bishop, from West Maui, and differs 

 from all other Hawaiian lavas I have analyzed in its small con- 

 tent of iron and of titanic acid. 



No. 4 is a highly vesicular, red lava from the ejecta of one 

 of the numerous cinder cones on the Kohala mountain. Here 

 again, in a more recent lava, we find the proportion of bases 

 and that of phosphoric acid increased. It seems probable that 

 the soil No. 3 originated from volcanic ash ejected from these 

 same cinder cones, the proportion of phosphoric acid being 

 there still higher. 



No. 5 is also a lava from the Kohala mountain (the oldest of 

 the Hawaii mountains, but recent in comparison with the 



