234 EDWARD B. MATHEWS 
Summit types, and it does not appear to be as commonly devel- 
oped. Ledge exposures of this type are comparatively rare, as 
The 
relatively greater resistance to weathering, due probably to the 
more compact texture of the rock, is clearly brought out in the 
When the fine-grained 
granite occurs in any considerable mass it forms the tops of 
minor hills and ridges. 
the solid rock is usually covered by angular bowlders. 
topographic position of its exposures. 
This is well shown in many places 
within the area of the map, the best illustration occurring on the 
subordinate ridges of the slopes of Pikes Peak and in the rugged 
area between Grouse Hill and Red Mountain, on the sides of the 
canyon of Crippie Creek. 
TABLES SHOWING THE COMPARATIVE ABUNDANCE AND SIZE OF 
THE CONSTITUENTS OF THE DIFFERENT TYPES 
The comparative abundance, size, and development of the 
various constituents in the four types of granite described in the 
preceding pages, are summarized in the following tables : 
TABLE I. SHOWING RELATIVE ABUNDANCE OF MINERALS 
Pikes Peak Summit Cripple Creek Fine grained 
OWA > coco odod abundant abundant abundant predominant 
Microcline...... predominant predominant predominant predominant 
Orthoclase ..... fairly commonly 
Oligoclase ..... constant constant constant constant 
Perthitic 
intergrowths..| well developed | unusual not marked 
Micropegmatite .| very rare very abundant | rare present 
Hornblende.....| present 
ISSIOWUWS 5 o'c 0g ooG6 abundant abundant present present 
Muscovite...... common 
IMBC scasecoe rare very marked | present 
EN OBUINWS 6660.09 06 constant rare eUEE present 
Zi conmeeee oe constant present constant constant 
Pibitamnite erent present 
Eipidoveranennicr rare present 
Magnetitemennic: present rare present present 
Hematite ...... present present present 
