PHYSIOGRAPHIC DEVELOPMENT IN COLORADO 



127 



DESCRIPTION AND CLASSIFICATION OF PHYSIOGRAPHIC UNITS 



I. The first unit extends for about 12 miles from the Con- 



Beginning 



Prospect Mt: 



The Needles 



Sec f /on fra/77 fiorth to South 



thf~u £s t&s \/<2//ey 

 ^a^i^ 0/ £stes P'tyr-''c i/z/Za^e 



Secf/on /^f-cfnn /Yo'-/'/i fo Soo/'/> 

 3 Afr/es wes^ of- l?f-aM-e 



Pa/isade Mt. 



Secfyon /rorn /Voft/j /<? Soutfj 

 thru 7~hon7jpson l^a/Zey 

 / Afi/e east- of Oz-a^e 



tinental Divide east through Moraine Park (Fig. 6). 

 at the Continental Divide 

 the first unit is typical of 

 the topography developed 

 by late Pleistocene glacia- 

 tion. At present the tribu- 

 tary in Spruce Canyon 

 harbors the Sprague Gla- 

 cier — a remnant of the 

 larger masses of ice which 

 grooved and scoured the 

 granite and schist of 

 stream-carved canyons 

 into U-shaped valleys with 

 many hanging tributaries. 

 The chief tributary once 

 occupied by the late Wis- 

 consin ice is the Fall River, 

 the lower part of whose 

 valley was the melting 

 basin (Horse Shoe Park) 

 of an ice tongue similar to 

 that which filled the Big 

 Thompson in Moraine 

 Park and developed huge 



lateral moraines. Fig. i.— Diagrammatic cross-sections of the 



' 2. The second unit valleys of units 2, 3, 4, and s of the Big Thompson 



J.1 ■T' X ir 11 River Valley, 



comprises the i^stes Valley. 



This area has a broad, flat T-shaped outline. From Moraine Park 



to Estes Village the valley is from i to 2 miles wide. East of the 



Village it widens and lengthens north to Devils Gulch and south 



to include Fish Creek Valley. On all sides of this broad, flat 



surface granite walls rise abruptly so that for a distance of nearly 7 



miles the valley is marked at its margin by precipitous granite cliffs, 



i.e., the Needles in Estes Park (Fig. i). 



.Section froni /V/V to SE. 

 Tlhru Tyyo/n/fsor? Canyon 

 ^ A/r/es east of Afont/fose 



