ROCKS ABOUT CANYON CITY. 155 



contact of the sandstone with the subjacent pre-Paleozoic rocks and with 

 the superjacent shales and limestone; views were also obtained of the 

 entire section from this point to the overlying Carboniferous limestone. 

 After my return a brief notice of the presence of an icthyic fauna near 

 Canyon City, Colorado, in association with an Ordovician fauna was read 

 before the Biological Society of Washington on February 7th, 1891. 



Description of the Locality. 



( anvon City, Colorado, is situated near the southwestern shore of a bay 

 of early Silurian (Ordovician) and probably also of pre-Cambrian time. 

 The outcrop of pre-Cambrian rocks of the Rocky mountain front breaks 

 away south of Pikes peak and sweeps with a broad inward curve to the 

 westward, and thence southeastward past Canyon City before extending 

 eastward to the meridian of Pikes peak. Along the central part of the 

 western shore of this bay sediments were deposited, in Silurian (Ordovi- 

 cian) time that at present form massive beds of sandstone and limestone 

 extending several miles northward and southward on the flanks of the 

 pre-Cambrian or Algonkian rocks west and northwest of Canyon City. 

 The valley of the Arkansas river cuts the outcrop a mile wesl of the town 

 and erosion has removed it in places, but it is practically continuous for 

 ten miles north of the river, and isolated outcrops occur three miles 

 southward toward and into Webster park. The typical section was 

 measured in the immediate vicinity of Harding's quarry, which is about 

 one mile northwest of the state penitentiary at Canyon City. 



The Hakdixo Quarry Section. 



The section begins near a spring a little way west of the Harding sand- 

 stone quarry, and is carried on the strike of the beds so that it terminates 



nearly a mile north of the quarry. This is done in order to secure con- 

 tacts from layer to Layer all the way from the base to the summit. The 

 basal bed of sandstone rests unconformably upon Algonkian bedded 

 gneiss and micaceous schists that dip to the eastward at high angles. 

 60°-75°. The succession is as follows: 



Feet. 



I . <i — ( !oarse, light gray sandstone 5 



l) — Compact thinly bedded reddish anil gray sandstone passing into a 

 -ray ami more massively bedded somewhal friable sandstone thai 

 changes, a1 "_'•"> feel up, into a purplish-tinted somewhal coarse fria- 

 ble sandstone (strike, X. L0° E. (mag.) ; dip, 40 E.) 33 



Fossils. A few scattered fish scales were noticed in the purple 

 beds ami Lingula attenuata, Salter (?), 20 feel from the base. 

 The beds are penetrated by an immense number of annelid 

 borings, ami the surfaces of the purplish-tinted layers are often 



