ENDLicH.] "monuments" GLACIATION. 115 



short space of time, they soon succumb under the combined attacks of 

 their assailants. Tlie frail support of shales ere long grows too weak to 

 sustain the weight of the capping sandstone, and when this has fallen 

 off nothing remains save a small mound of decomposed shale to mark 

 the former existence. Both this " species" and the one above mentioned 

 might be termed normal monuments, in contradistinction to the succeed- 

 ing ones, which are accidental. 



Kear Antelope Park, on a small tributary of the Rio Grande, lies hid- 

 den a spot of unequalled grandeur and beauty. Instead of small monu- 

 ments, at best 12 to 14 feet in height, we here have them rising to 300 

 and 400 feet. Towering far above the surrounding spruce timber, they 

 lift their weather-beaten heads toward the sky. Thousands of others, 

 that appear as pigmies by the side of giants, stud the entire locality. 

 Precipitous walls, 600 feet in height, enclose, as though guarding them, 

 the wonderful groups here displayed. Arches and gateways of ample 

 dimensions, carved by the skillful hand of nature into projecting walls, 

 permit a distant view that is closed only by the sharp summits of the 

 coDtinental divide. Similar to the spires of ancient gothic architecture 

 do the monuments at places rise in isolated glory, seeming larger even 

 than they really are from their very position. A trachytic conglomer- 

 ate furnishes the material for these admirable forms. Erosion and abra- 

 sion along the steep walls cause some huge bowlder to project. On 

 either side downward the softer portions of the conglomerate are worn 

 away, until finally, as if growing out of the wall, we find the completed 

 monument. 



In 1874 still another kind was observed. From an adjoining bluff 

 large bowlders of basalt had rolled down upon a gentle grass-slope. 

 They rested accidentally upon the surface of a very soft trachytic tuff. 

 Eain and temporary streams cut away the easily-yielding material until 

 nothing remained of it but slender columns, 20 feet in height, that bore 

 upon their tops the erratic bowlders which had protected them from 

 total destruction. These two last species I term " accidental," as the 

 physical composition of the conglomerate is certainly an accidental one, 

 and as the last owe their existence purely to the stopping of the erratic 

 bowlders at that particular locality. 



GLACIATION. 



In the report of 1875 I have given a synopsis of the glacial evidences 

 observed within my districts during the past years. The presence of 

 ancient glaciers in Colorado is made apparent by the existence of mo- 

 raines, by the grooving, striation, and polish of rocks inpositu, and by 

 the formation of numerous lakelets. In ])revious papers I have asso- 

 ciated the existence of glaciers in Colorado with that of large lakes and 

 inland seas farther west. Dependent upon the disappearance of these, 

 I have regarded the extinction of the glaciers. Wherever the condi- 

 tions were favorable, i. e., a good locality for the accumulation of snow 

 and ice oft'ered itself, there we find the traces of former glacial activity. 

 Not unfrequently the arrangement of moraines is perfectly typical, and 

 the rocks, polished and grooved, appear to be fresh as the glacier has 

 left them. Vegetation has not yet sprung up in many of the places 

 where the soil was all carried away by the moving ice. Streams flowing 

 through and from the glaciers {Gletseherbach of the Germans) have worn 

 deep channels into yielding rocks, and, often being dammed, have formed 

 glacial lakes. 



So far as can be determined, glacial activity existed in Colorado before 



