Crawford.] 556 ["^'^y '5. 
tiiiued raiiit':ills. Dcvitirficatioii and alteration of miiu'rals and 
masses of lava into palagonite and laterite, and also metasomatie 
chanojes, are found at several places both north and south of the 
Cerro. 
The early genetic history of the Cerro, studied in connection 
and correlation witli the geological features and structure of the 
province or part of the Pacific coast in Nicaragua, presents 
numerous points of much interest, especially in regard to the 
volcanic activity; e. g. (1) The deposits of Jurassic and Cretaceous 
coals found a few leagues north of the Cen-o, and formed on 
magnesian limestones of the Paleozoic era, with thin strata of sand 
and clay intervening^ and covered by several thickly laminated 
sheets of volcanic extrusions deposited during a subestuarian 
activity ; some of this coal has been softened by heat, and, while 
in that condition, was sprinkled with sands and cinders. (2) 
Exposures caused by upheavals and faulting disclose many inter- 
stratifications of clastic deposits and volcanic materials, which 
were made during submarine activities since the Mesozoic era, 
and which continue through the valley in which the Cerro is 
located. (3) At two places it was noticed that the continuity of 
the volcanic submarine strata and their color and mineralization 
were quite different from those of other parts of the deposit in 
the same zone. This peculiar deposit is a hard arenaceous claj% 
its color, through the presence of an aluminate of gold (An Al), 
varying from pink to purple. It appears that the volcanic condi- 
tions of greatly heated chemical vapors caused the auriferous 
clays and quartz composing the gangue of some auriferous fissure 
or " lode " to form, in part, a chemical union of aurum and 
aluminum, an ore of gold. (4) For about a hundred miles from 
the shore line of the Pacific Ocean near Cerro Viejo west into the 
Ocean, there is a depressed area, still sinking, which extends south 
along the western coast of Nicaragua and Costa Rica, from about 
lat. 14° N. to lat. 10° 30' N. This depression is, most probably, 
coeval with the beginning of Cerro Viejo, Coseguina, and Momo- 
toniVjo, and is filling up as rapidly as it descends with disintegrated 
volcanic ejectamenta transp<)i;ted into it by rain floods from south- 
ern Salvador and Honduras and western Nicaragua and Costa 
Pica. It is quite ])i-ol)able that the heat, which, if allowed to 
