E54 E, P. CAREY AND W. J. MILLER 
The surface of the serpentinized area is hummocky and often 
almost destitute of soil, which character aids in determining the areal 
extent of the serpentine. 
THE DIORITES 
Occurrence and relations.—The Diorite occurs in dikes intrusive 
into the older pyroxenite—peridotite rocks and gabbros. ‘The best 
exposure is to be found in the quarry. The dikes here constitute 
Fic. 1.—North face of Quarry Hill, showing diorite dikes in pyroxenite, gabbro, 
and serpentine. 
two sets: an older set of five nearly vertical dikes, averaging about 
three and a half feet in width and parallel with each other, inter- 
sected by another set of parallel dikes, averaging about four and a 
half feet in width and dipping toward the northwest. 
The relations of these two intersecting sets of dikes are now, 
since the field-work was done, rather obscure, on account of a talus 
that is beginning to cover up some of the intersections; but some 
intersections are still apparent, as is evident from the photograph, 
and the relative age was plainly evident when the work of quarrying 
the diorite was in progress. 
