teratice Cambrian Fossils.— Woodworth. 943 
But perhaps I am unable to do justice to Mr. Fisher's views as 
I feel insurmountable difficulties in looking at the problem from 
his standpoint. 
We have now almost exhausted the catalogue of initiatory 
compressive agents invoked by various authors for the production 
of mountain ranges. It remains to consider a final one, namely, the 
intrusion of molten matter into the crust, and the detrusion and 
throwing back of the upper strata due to the forcing up of tongues 
or folds of the strata below. These agents can, however, be only 
secondary effects of expansion or compression, not initiatory 
forces. Nevertheless they play a very important part in the fold-— 
ing and building up of a mountain range which I have explained 
very fully in the ‘Origin of Mountain Ranges.” 
I trust I have now said enough to show that simple expansion 
by increase of temperature is by far the most potent of any 
known cause in the production of lateral pressure in the earth’s 
crust. If to this we add recurrent expansion and the other 
agencies I have endeavored to show from geological and physi- 
cal data are concerned in the building of a mountain range, we 
arrive at a satisfactory solution of the great problem of the fold- 
ing and elevation of mountain chains. 
Jan, 18, 1892. 
NOTE ON THE OCCURRENCE OF ERRATIC CAM- 
BRIAN FOSSILS IN THE NEOCENE GRAV- 
EES OF THE ISLAND OF MARTHA’S 
VINEYARD. 
By J. B. Woopwortu, Somerville, Mass. 
In the course of an examination of the dislocated Neocene® strata 
of the island of Martha's Vineyard, carried on under the supervision 
of Prof. N. 8. Shaler, for the U. 8. Geological Survey, during the 
summers of 1889 and 1890, I collected a number of chert peb- 
bles from the white quartz gravel or ‘‘osseous conglomerate” of 
Gay Head, and from an outcrop of the same age in the village of 
West Tisbury. Several of these specimens proved to be fossilif- 
erous; one from the locality in West Tisbury contains a_ fossil 
which, on close examination, is seen to be the zoantharian coral, 
Ethmophyllum, Meek, of the Lower Cambrian. 
*Neocene is here used to designate the Miocene strata of Gay Head, 
See 10th annual Rept. U. 8. Geol. Survey, p. 65. 
