98 CAKBONIl'EBOUS l^-ORMATIONS AND FAUNAS OK COLORADO. 



feet thick, aiul contain.s OphUeta, Camarelhi, ami a few other invertebrate fossils 

 characteristic of the Lower Silurian formation in the section at Manitou Springs and 

 at i\Ianitou Park, whence the name is derived." In the northern part of the quad- 

 rangle this limestone is not dolomitic, and is connected directly with the tj^pical 

 locality at the north end of Manitou Park. In the southern part of the quadrangle 

 the Manitou limestone is immediately overlain by the Harding sandstone, which is 

 predominantly a hne-grained, saccharoidal sandstone in alternating banks of light- 

 gray and pinkish or variegated colors, and sometimes calcareous at the base. The 

 maximum thickness is about 100 feet. This horizon is characterized by numerous 

 remains of fishes of types not elsewhere found below the Devonian, and it carries 

 also a rich invertebrate fauna of Trenton age. "The Harding sandstone is not found 

 in Manitou Park, nor at Manitou Springs, and has not been identified at an}- other 

 locality." In Garden Park the Harding sandstone rests with apparent conformit}' 

 upon the Manitou limestone, but evidence elsewhere indicates that before its deposi- 

 tion the Manitou limestone was subjected to a period of erosion. 



Succeeding the Harding sandstone with apparent conformit}' there occurs a 

 bluish-gray or pinkish dolomite which has a thickness in Garden Park of about 100 

 feet, but increases southward, and near Canyon reaches a maximum of 270 feet. 

 This is partly through the development of an upper and highlj- fossiliferous member 

 not seen in Garden Park. The Fremont limestone in Garden Park is especiall)=' 

 characterized by Halysites catemdatus, and it also contains a large invertebrate fauna 

 like that of the upper Trenton of New York. This limestone horizon has not been 

 recognized in other sections of Paleozoic strata along the east base of the mountains, 

 nor has its equivalent been found in any other part of the West. Its present limita- 

 tion eastward from Garden Park, on the slopes of the range, is by erosion, which 

 took place after the deposition of the Millsap limestone. 



The long period between the deposition of the Fremont and the Millsap seems to 

 have been one of elevation and erosion, though there is seeming conformity between 

 the two limestones in local exposures. Of the Millsap itself only remnants are found 

 resting upon the Fremont limestone in Garden Park and along the western line 

 toward Canyon. The formation is now represented by about 30 feet of thinly 

 bedded, variegated, dolomitic limestone, with a few thin sandstone layers. Chert 

 nodules in the upper part carry a limited fauna, elsewhere described. 



The Fountain formation includes a series of red sandstones, grits, and conglomer- 

 ates, a part of the so-called "Red Beds." The typical localitj' is in the northern part 

 of the quadrangle, but it seems to have essentially the same lithologic characters in 

 Garden Park. The thickness is estimated at nearly 1,000 feet. The Fountain beds 

 rest unconformably upon the edges of the entire Silurian section in Red Ridge, at 

 the upper end of Garden Park, and along the southern end of the Colorado Range 



