Zt*-) reet— Otiocolflle shale and sandsiooe. 



K.hwest lh» pioportlon ot whitt beconiM SIMI 

 Rrefller ) 



90 feet — Brownlsb red sliale 

 1 (001— Black cailioiiiiccous shale (oil of mlnule eypsura "elns. 



386 E. HUNTINGTON GLACIAL PERIOD IN NON-GLACIATED REGIONS 



permanent bodies of stand- 

 ing water, two hypotheses 

 present themselves : Either 

 the white layers indicate 

 successive brief encroach- 

 ments of the sea, or they 

 preserve the record of a 

 strophic period during 

 which parts of the floor of 

 an inclosed basin were 

 alternately exposed to the 

 air and covered by the 

 waters of a lake. Accord- 

 ing to the first supposition, 

 the land moved gently up 

 and down time after time, 

 or, more probably, sank by 

 steps. At first a given 

 area was above sealevel and 

 was covered with red de- 

 posits ; then, perhaps be- 

 cause it had become loaded 

 with sediment, it sank 

 slightly below the sea. 

 Deposition still proceeded, 

 though now the deposits 

 were of a light color. " At 

 length they accumulated so 

 • that their top reached the 

 surface of the sea; there- 

 upon the deposits became 

 red, and so continued until 

 the land sank again, and 

 the process was repeated. 



This hypothesis, postu- 

 lating, as it does, that the 

 land sank by steps, is 

 generally accepted in ex- 

 planation of the alterna- 

 tion between coal measures 

 and barren measures. As 



300 feet— AlletnaclOE sort red sliale aod Haider "hl'e »', "" 

 " " green stiale. red predomlnatlUB. 'Oie wbltc layers 



are gypslferous. 



S leet — Brown sandstone. 

 22 feet — Soft reddish brown sandy shale 

 8 feet — Brown sandstone. 



45 feet — Soft reddish blue shaly sandstone. 



10 feet— Brown (calcareows) sandsiooe. 

 15 feet — Soft gray (calcareous) shale. 



Iflo feet— Soft red shale 



20-30 feet— Variegated Ri.Be. /luli.ci/ shales, soft yellow wllli 

 bands of gypsum, tlieo pink, antl, at base, blue, 



30 feet — Coarse calcareous conglomerate tSupcr-Aubrcu), 



Yellowish Aubrey limestone iCarboitttfrouat. 



FiGDRD 16. — Section of the Mnencopie Shales near 

 Virgin City, Utah. 

 Virgin City is near the western end of tlie southern 

 border of Utah, 12 miles south of the locality repre- 

 sented in figure 15. Scale : 1 inch = 160 feet. 



