January, 1900. Teller— The HAMiLTOft Formation. 
53 
Number eleven is the one layer in the formation that has prob- 
ably the strongest characteristics ; it is the heaviest-bedded layer, 
being 33 inches in thickness and is exceedingly hard as it con- 
tains a large quantity of calcite and pyrite, with occasionally a little 
zinc blende. The organic remams have been very numerous, many 
of them probably corals, having been absorbed and the cavities filled 
with the minerals mentioned. Fossils of the Cephalopod order pre- 
vail, large forms of Gyroceras and Gomphoceras are abundant, 
whileof Brachiopods the Spirifer,Orthothetes 2indAtrypa are com- 
mon. Lamellibranchs of several species make their appearance. Al- 
most all of the above are in the form of internal casts, very few of 
the fossils preserve any of their external markings, while fish re- 
mains are at times to be found, being probably more numerous 
than in any' layer above number four. 
Number twelve may properly be termed the rotten layer, it is 
about 10 inches thick, very earthy in character and readily goes 
to pieces ; the fossils are less numerous than in number eleven, 
although of the same general species, while Orthoceras are more 
numerous than in any other layer. 
Numbers thirteen and fourteen are each about 10 inches thick, 
and while slightly different in aspect are generally about the same. 
They are harder than number twelve with a tendency to split up 
into a number of minor layers, the fossil contents are numerous ; 
a few new forms appear, while of the large Cephalopods, Gyroceras 
and Gomphoceras have disappeared. Many of the fossils have 
their shells replaced with iron which is much oxided and there- 
fore poorly preserved, while many others on weathering are found 
in a very good condition ; many of the corals have been absorbed 
and replaced with calcite with which are at times associated a little 
nickel in the form of Millerite. A few impressions of plant re- 
mains are found ; most of the Gastropods of the formation are 
confined to these layers, none having been noted in the lower 
ones, while the Blastoids begin and end their existence in them as 
far as noted. 
Number fifteen has much of the characters of the two below it, 
is probably a little more oxided, has the same tendency of breaking 
into minor layers, being at times either angular or lumpy in its 
breakage. It also has the feature of becoming shaly but is not 
continuous ; it is rather earthy, has less organic remains than the 
two layers below it, the same species being found while 
a few new ones appear, the most characteristic of which are the 
Terehratula. 
Number sixteen is about 10 inches thick, is more compact 
than number fifteen, has the same tendency of minor layers and of 
lumpy and angular breakage, but contains not so much iron or 
