st. JOHN.) GROS VENTRE BASIN CONGLOMERATE. 227 
The apparent local occurrence of the conglomerate, which is, so far as 
known, restricted to the region north of Gros Ventre Mountains, would 
suggest the environing mountain ranges, the Teton, Gros Ventre, and 
Wind River, as the sources whence its component materials were de- 
rived. Observation, as yet, is too limited for the purposes of tracing the 
physical history of the horizon and noting the changes in the component 
materials remote from the ancient shores of the basin in which they were 
deposited. The beautifully rounded condition of the hard quartz frag- 
ments and the thorough comminution of the softer rocks which are 
mingled with the deposit in the condition of fine sand and limy cement, 
evidently show the work of wave action. At present the deposit has not 
been observed in immediate contact with the rocks in the mountain bor- 
ders whose degradation contributed the materials, so that it is not known 
to what extent the trituration of these materials had progressed along 
the immediate shore. The peculiar conglomerate in the region of the 
northern end of the Hoback Canon ridge on the south slope of the Gros 
Ventre Range, described ona preceeding page, possesses in a marked man- 
ner the peculiarities of a shore deposit, from which the softer rock frag- 
ments have not been eliminated or so completely reduced by attrition as 
is the case in the Gros Ventre Basin conglomerate; but here the data 
in hands, so far as relates to tracing identity with the latter formation 
cease, although that deposit is also of Tertiary age, but presumably of 
later date, or Pliocene. 
