70 ANNALS NEW YORK ACADEMY OF SCIENCES 



Feet 

 Shales, slaty, black, alternatiug with shaly bitumiuous sandstone ; inrti- 



vidual layers less than 2 feet thick 16 



Sandstones, yellowish or greenish, with shaly layers 14 



Quartzite, dense, gray 6 



Shales, sandy, black; and fine-grained sandstones, largely quartzitic, thin 



bedded 23 



Quartzite, hard, white 20 



Sandstone, friable, white, containing clay 10 



Porcelain shales and thin argillaceous sandstones 21 



Shales, fine-grained near top, dense, porcelain-like below, with sandy 



layers 42 



Quartzite, massive, white, more friable below, with thin clay layers near 



base 5 



Sandstone, coarse, white, lower portion indurated and containing a 2-foot 



shale layer 13 



Shale, green, with some purple and gray layers, very fine grained, much 



of it hard like porcelain ; some sandy layers, more numerous near base ; 



dark red; rests upon 5 feet of very white and massive porcelain shales. 50 



Shale, red, sandy and containing shaly sandstone 16 



Green and red porcelain shales and sandstones with a 2-foot pink, fine- 

 grained limestone at the top 78 



Sandstone, massive, green above, white below 5) 



Sandy shales and shaly sandstones, gi'eeu, white and red 69 



Sandstone, white, saccharoidal 20 



Sandstones and sandy shales, with some porcelain layers, red and green . . 26 



Sandstone, massive, fine-grained, gray, white 10 



Sandy shale and sandstone, alternating green and red 20 



Sandstone, fine, greenish white, becoming red and shaly below 17 



Sandstone, extremely massive, white ; red stains from shales above ; 



quartzite in lower part and a thin green shaly layer near base 70 



Sandstones, with thin limestones and calcareous shaly layers ; some reds 



and pinks, prevailing colors buffs and yellows 120 



Sandstones, heavy bedded, saccharoidal 11 



Shale and thinly bedded buff sandstone 10 



Quartzite, light colored, with bluish stains 18 



Sandstones and shales, red 65 



779 

 La Plata sandstone. 



In the La Plata quadraiigie the Morrison (McElmo) is descrihed by 

 Cross, Spencer and Purington (1899, 4) as a series of alternating shales 

 and sandstones, from 400 to 500 feet thick. The sandstones are usually 

 characterized by the presence of green shale flakes; 50 or 60 feet below 

 the top of the formation, there is a bed of coarse white conglomerate 

 separated from the "Dakota" by a series of red and green shaly beds. 

 The conglomerate contains white and dark quartz pebbles, and is 10 to 15 

 feet thick. 



