of the Specular Iron-Ores of Santiago de Cuba. 423 
the igneous flood down the Sierra slope from the overflow of 
innumerable dykes. The implication of the corallines in the 
wa 
@ 
now sometimes represented by chloritic kaolin. am 
disposed to refer to ramifications of the eruptive material in 
the act of overflow and upheaval. 
2. The ore-bodies, whose general position is thus to be 
defined, occupy the thinning edge of the dioryte mantle. How 
far its reduced thickness is due to erosion, and how far to its 
original development, or to the circumstances of its flow, is par- 
tially indicated by the degree of erosion which the ore-bodies 
themselves have undergone. All that have been discovered 
s. 
Unequal elevation or unequal erosion, or probably a combi- 
nation of both conditions, has served to introduce a series of 
conditions unfavorable in certain cases to the radical alteration 
of coralline masses. In such cases the coralline mass occurs in 
the form of white marble. In attitude and general, relations 
both with the syenyte and dioryte such masses have only cer- 
tain features in common with the ore-bosses. They have’ 
already been described as devoid of stratification, and as 
ge, a 
tributed. Under such circumstance all drainage both from 
by this rock under such conditions, it will be noted, is by 
induction. Replacement of calcareous matter has gone on 
Am. Jour. Sct.—Turrp Szrres, Vou. XXVIII, No. 168,—Dxc., 1884. 
27 
