3-12 DRAKE — tup: geology of IXDIAX territory. [Sept -A, 



boniferous in age. In texture, color and mineralogical composition 

 many of the Missouri granites closely resemble those of the Spav- 

 inaw area. The resemblance is especially true of the granophyric 

 and micropegmatitic texture. Dr. Haworth says : ^ '' The distribu- 

 tion of rocks exhibiting such structure is very wide; there is 

 scarcely a granite in the State in which portions of it are not rep- 

 resented The small outlying granitic areas generally have 



this structure throughout This structure is common in the 



porphyries also." '" 



Iron oxide is a rather common constituent of the Missouri 

 granites, and is especially common in the porphyries. ' These 

 properties in general are also characteristic of the Spavinaw rock. 

 The age of the Missouri granite, however, is apparently different 

 since it has been referred to the Archean. ^ 



Clastic Rocks. 



The clastic rocks which cover all this area, except the small dike 

 described, belong to the Silurian, the Lower Carboniferous, the 

 Coal Measures and the Permian. 



The Silurian occurs in a few narrow valleys in the northeastern 

 part of the area. The Lower Carboniferous covers about half of 

 the Cherokee Nation, or the northeastern part of the field under 

 discussion. The Coal Measures cover all the rest of the area except 

 a narrow strip along the western edge, which is Permian. 



Silurian. 



The Silurian areas lie in narrow strips along valleys in the 

 Cherokee Nation, where stream erosion has cut down through the 

 overlying Lower Carboniferous beds. In some places folding has 

 elevated these lower beds so that erosion has more readily exposed 

 them. 



Structure. — The Silurian strata lie almost horizontal and closely 

 conform to the inclination of the overlying Lower Carboniferous 

 beds. 



LWiology. — The strata are composed of saccharoidal sandstones, 

 marble or highly metamorphosed limestones, chert and dolomitic 

 calcareous sandstones. 



1 Mo. Geol. Stir., Ann. Rept., 1894, Vol. viii, pp. 165-166. 



"^ Ibid.,^. 193. '^ Ibid., pp. 141, 188. ^ Ibid., pp. 95-96. 



