422 Editorial Comment. 
sonable doubt that the crystalline rocks are the elder. The 
characters of the several associated rocks are those which one 
finds united in very many Archa?an regions throughout the 
world. The products of alteration of these rocks are similar 
to those which one finds in the districts just alluded to. The 
chemical peculiarities of the iron ores found in contact with 
these rocks are similar to those which one finds in the ores 
of the Archaean regions, both in the low percentage of phos- 
phorus and in the pyrite and (more sparingly) chalcopyrite 
disseminated through the ore, and in other respects. If this 
nucleal mass had been forced up from the earth's interior in a 
state of igneous fusion, there would not be now (as there are) 
abundant cases of stratification and structure, implying an orig- 
inal sedimentation. If this mass had resulted from volcanic 
outflow, there must have been contact phenomena, and changes 
induced on the surfaces of the rocks with which it was brought 
in contact. No such contact alteration has been observed 
between these rocks and either of the three groups which meet 
them. The direction of the range, considered as a whole, lends 
support to the hypothesis that it is a fork of the Andes which, 
diverging from the main axis in Guatemala, traverses the pen- 
insula of Yucatan, and in a symmetrical curve sweeps through 
the highlands of Cuba and Jamaica, Hayti, Puerto Rico, the 
Windward islands, and the north-east coast of Venezuela. This 
run of high land once enclosed the Caribbean as another Medi- 
terranean sea. The shapes of the hills of this range, produced 
by weathering, are not those usually visible in regions of vol- 
canic, but rather of metamorphic, rocks. The rocks which fur- 
nished the basis for the above conclusions are all, or nearly all, 
alteration products. In some cases they appear to be the result 
of a second, third, or even greater number of metamorphoses, 
some of their constituents seeming to pass through cycles of 
change, ending in the mineral with which the alteration began 
after a number of intermediate stages. The rocks are diorytes, 
with epidote, porphyritic dolerytes, which resemble and have 
been taken for syenites, garnet rock, actinolite, felsy te and ortho- 
felsyte porphyry, like that of the South mountain of south- 
eastern Pennsylvania, of St. David's Head in Wales, and else- 
where. To these are added pyrite and iron ores. Copper and 
manganese ores are not rare, but their relations to the rocks 
under consideration have not been made out. 
