178 Kansas Academy of Science. 



Correlation of the Formations Described in the Fort Apache 

 Region in Arizona with Similar Formations in Other Parts 

 of the State. 



Albert B. Reagan. 



On page 152 of Professional Paper 98-K of the U. S. Geological Sur- 

 vey, Dr. Frederick Leslie Ransome says, in speaking of my work in the 

 Canyon creek section' (Arizona), that attempts to identify in my pub- 

 lished sections the formations discriminated in the Roosevelt and Grand 

 Canyon sections have met with little success. - 



As my field work as well as Gilbert's was done before anything much 

 was really known of the geology of that part of Arizona, the sedimentary 

 rocks were mapped and described in groups, as it then appeared im- 

 practicable to map them in as great detail as has since proved possible 

 in the Ray quadrangle, for instance. Furthermore, on account of the 

 advanced knowledge of the geology of the entire region, certain peculiar 

 formations which were then difficult to identify can now be readily 

 placed by comparing them with stratagraphic work in other sections. 



The following sections of the Palaeozoic strata of Arizona from Mexico 

 to the Grand Canyon have been made:-"* Bisbee,^ Tombstone,^' Clifton,^ 

 Globe and Ray Quadrangles,' Roosevelt,^ Southern,'^ Part of the Sierra 

 Ancha,io Northern Part of the Sierra Ancha,'' Head of Canyon Creek.i- 

 Jerome region, i'' and Grand Canyon. i-^ 



By a comparison of these sections it is easily seen that Gilbert did 

 not see the entire Cambrian series at Canyon creek and that his Tonto 

 Sandstone, as with my sections, is the upper part of the series. His sec- 

 tion at the head of Canyon creek was often visited by the writer, and 

 from appearance all he examined at this point was the Dripping Spring 

 quartzite and the Barnes conglomerate; the rest of the series is wanting 

 at this point and the Dripping Spring quartzite is in itself not its full 

 thickness. Gilbert's section is on the crest of the east and west older 

 pre-cambrian ridge that underlies the Palaeozoic here and now extends 

 as the surface rock from near Ellison P. O. westward through the Tonto 

 basin, covering a region from five to fifteen miles wide. In mapping 

 the formation the writer followed Gilbert and considered the forma- 

 tion below the Barnes conglomerate as Algonkian. But in the light of 

 later investigations it is the lower part of the Cambrian series and is 

 included in the Tonto group of Noble's Grand Canyon section. Several 

 miles down Canyon creek from where Gilbert took his measurements the 

 Pioneer shale comes to view beneath the Barnes conglomerate. The 



1. Reagan, A. B., Geology of the Fort Apache region in Arizona. Am. Geologist, vol. 

 32, pp. 265-308, 1903. 



2. Ransome, Professional Paper 98-K of the U. S. Geological Survey, p. 152. 



3. Ransome, Professional Paper 98-K, plate XXV. 



4. Ransome, P. L., U. S. Geological Survey, Paper 21, 1904. 



5. Ransome, F. L., from unpublished data. 



6. .\fter Lingren, W., U. S. Geological Survey, Folio 129, 1905. 



7. Ransome, P. L., Washington .\cademy of Sciences Journal, vol. 5, pp. 38()-::i88, 

 1915. 



8. Ransome, F. L., from unpublished data. 



9. Ransome, F. L., from unpublished data. 



10. Ransome, F. L., from unpublished data. 



11. Gilbert, G. K., Wheeler Survev, vol. 3, pp. 163-164, 1875. 



12. Ransome, F. L., from unpublished data 



IZ. Kansome, r. i-i., irom uiipuuiisneu uniit. 



13. Based chieflv on work of L. F. Noble, U. S. Geological Survey, Bulletin 509, 

 plate X, 1914. 



