FOSSILS OF THE FREMONT LIMESTONE. 157 



Page. 

 Fossil*. — The lower layers are, in places, made up largely of 

 the casts of corals and inollusks, but well preserved specimens 

 are rare. Corals were observed in abundance in the lower LO 

 feet of the limestone on the northern side of the road leading 

 from Canyon City to Parkdale, a little east of where it enters on 

 the pre-Paleozoic rocks. In the lower three feet at the Harding 

 quarry and immediately toward the north there have been col- 

 lected the species mentioned in the list, pages 159, 1(50. 



4. " — Tlii' upper portion of 3 passes into a hard, compact, light-colored lime- 



stone 45 



Fossils. — Zaphrentis and fragmentary casts of gasteropoda. 



I/ — Dark reddish-brown sandstone 10 



'• — Compact, hard light gray limestone breaking into angular fragments 

 and with a band of purple and gray calcareo-arenaceous shale at the 



hase 45 



Fossils. — A large and varied fauna occurs of a Trenton type 

 (see list, pages 161, 162). 



5. Impure variegated banded limestone with interbedded sandstones and 



argillaceous beds 15-30 



Fossils. — Spirifera rockymontana, Athyris subtilita. 



Observations on tin' Fremont Lino stone Series. — The line of demarkation 

 between the upper beds of the Silurian (Ordovician) and the super- 

 jacent limestones in which Carboniferous fossils occur is not stronglv 

 defined, although it represents a long period of non-deposition and a 

 great time break. The Carboniferous limestones are sometimes brec- 

 ciated and lithologically unlike those below. No traces of the Silurian 

 and Devonian groups have been obtained. 



The bed of shale (number 2 of the section) is very persistent along the 

 six miles of outcrop examined. Fragmentary fish plates and scales occur 

 in the lower portion, but they were not observed in the upper part nor 

 in the superjacent limestones. The shale appears to include the closing- 

 deposit of the ichthyic fauna in this region. 



The basal layer of limestone resting on number 2 is in many place- 

 almost entirely made up of easts of fossils that crumble into a red dust 

 when the rock is broken. At a few localities they are better preserved, 

 and 54 species in all were collected. Traces of fossils occur all the way 

 through the 170 foot of impure limestone, but it is not until the upper 

 portion of number I of the section is reached that well-preserved speci- 

 mens occur, [n number 4c, 57 species have been recognized, only 7 of 

 which occur in number 3. 



Tlie el i a racier of the set limeiil s from the basal sandstone to the upper- 

 most Layer of limestone beneath the Carboniferous breccia indicates t hat 

 they were deposited in a hay or interior sea that was protected from the 

 <>p' 'I i ocean. A Iter the epoch of t lie a c< a 1 1 1 1 1 1 la t ioi i of t he beach sands and 



