134 Trans. Acad. Sci. of St. Louis. 



and were later especially noted by Dutton. 4 Gilbert 5 

 gave tlie first succinct account of the Black Mesa country 

 on the south. The details of the geological phenomena 

 presented at Coon Butte and the vicinity are fully ex- 

 plained by Foote, Gilbert, 7 Fairchild, s Merrill, 9 and 

 Telghman and Barringer, 1 " and the accounts of these 

 authors reference may be made. 



Significance of Certain Geologic Features. 



Geologic Section. The drill records of borings made 

 in the bottom of the Coon Butte crater are of exceptional 

 interest. As given by Messrs. Barringer and Telghman 

 the following section appears to be characteristic. 



Geologic Section of the Coon Crater. 



FEET. 



1. Soil, sand, surface material and wash from cliffs 27 



2. Lake-bed formations, lying horizontally and containing diatoms, 



shells of mollusks and abundant gypsum crystals 61 



3. Sand, which gives reaction for nickel and iron, and contains 



fragments of metamorphosed sandstone, sandstone, pumice, 



etc 135 



4. Sand and rock, sand-grains crushed slightly, if any, and not 



metamorphosed, barren of meteoric material 300 



5. Sand and "silica" (rock-flour), with abundant slag-like material 



containing iron and nickel and metamorphosed sandstone.. 80 

 6 Silica powder, fine (rock-flour), and sand, no meteoric material. . 20 

 7. Bed-rock, a grayish sandstone 



Character of the So-called Lake-Beds. Of the several 

 distinctive strata passed through in drilling numbers 2 

 and 5 are of noteworthy significance ; the last mentioned, 

 near bed-rock, on account of being the only zone in which 

 undoubted meteoric material occurs ; and the first because 

 of constituting the so-called lake-beds. 



4 Ann. Rept. U. S. Geol. Surv. 6:113. 1885. 



5 U. S. Geog. and Geol. Surv. W. 100 Merid. 3:128. 1875. 



°Am. Jour. Sci. III. 42:413. 1891. 



'Science, N. S. 3:1. 1896. 



8 Bull. Geol. Soc. America, 18:493. 1907. 



fl Smith. Misc. Coll. 50:461. 1908. 



"Proc. Acad. Nat. Sci. Phil. 57:861. 1906. 



