8 



GEOLOGY OF THE YELLOWSTOXE NATIONAL PARK. 



N umber. 



Feet. 



SH 



< 19 



f 18 



7t 



17 



a 





O 



16 





15 



5 



14 



a 





OS 





O 





fr 



Crowfoot Ridge section — Continued. 



c. Limestone, gray mottled with black, crystalline, in part magnesian, -well 

 bedded, in places crackled, and with much iron oxide and calcite. Strike 



N.70° W. Dip 30° N 70 



b. Limestone, mottled, gray and buff, very ferruginous in places. Beds 5 feet 



thick 30 



a. Limestone, white, crystalline, weathers cream, with granular surface and 

 indistinct fossil traces ; is magnesian and very finely crystalline. Forms a 



cliff, and is iron stained in places 35 



135 



Limestone, conglomerate, nodular, and shaly layers near the base, overlain by thick and 

 thin beds of densely crystalline limestone alternating with thinner, shaly and fissile 

 strata. Toward the upper part less shaly, denser, with brown layers and layers of 



very fossiliferous, crystalline limestone 40 



Shale, calcareous, thin ; purple, green, and brown 5 



Limestone, very argillaceous, buff brown, very fissile — 5 



Shale, greenish gray, very soft and crumbly 5 



Mottled limestone. The upper 2 feet is an arenaceous conglomerate, in which the frag- 

 ments are rounded pebbles of shale and sandstone; the matrix a slightly argillaceous 

 sandstone. Strike N. 70° W. Dip 27° N. The mottled limestone is a pure, thickly 

 bedded (20 feet) rock, dark gray mottled with brown or black; crystalline, with 



granular weathered surface of unchanged color 55 



' 13 Limestone, variously modified. The lower layers thickly and thinly bedded, much of it 

 coarsely crystalline, with green grains of glauconite and great numbers of trilobite 

 spines. Interbedded with this limestone are layers of dense, gray, fissile and thinly 

 bedded limestone, with yellow bands, aud limestone conglomerate. About the middle 

 of the beds there are several thick beds of crystalline limestone containing green 

 grains. This is overlain by a conglomerate. The matrix is pure limestone, the pebbles 



slightly argillaceous and resembling a mud deposit 100 



12 Shale, very thin, olive green and dark purple 150 



11 Limestone, pure and ferruginous. In general this limestone is red-brown, but contains 

 masses of dense, dark-colored limestone, which weather in balls with spherical shells. 



Balls 3 feet through 10 



f Limestone conglomerate; brown-gray and gray pebbles in buff matrix. Fragments T 



10 ^ 6llr0UIld6d 50 



Limestone, very similar to No. 9, and taking section to base of long ridge. Over these i 



I beds are layers of crystalline limestone, with green grains J 



9 Limestone, buff mottled with brownish gray; thinly bedded ~] 



8 Limestone, massively bedded, quite pure; weathers with smooth surface ; color, brown . [ 

 7 Limestone, pure gray, with dense, dark-gray layers and streaks in a buff', granular j 



matrix. Runs up to top of first point shown in PL II J 



6 Limestones, thinly bedded, light and dark gray in color, showing remains of shells and 



trilobites 10 



5 Limestones, thinly bedded, with interbedded micaceous shale, having fossil indications. 



Fossils collected from the upper part and from lowest beds 60 



4 Shale, micaceous, green and purplish 75 



3 Sandstones, slightly indurated, red and green, with grains well rounded ; quartzose 30 



2 Quartzite and sandstones, cross bedded, and containing well-rounded pebbles of gneiss. 100 

 1 Gneiss. 



