Udden — Castile Gypsum and Rustler Formation. 153 



Depth in feet 

 below surface. 

 From To 



Dark gray to. yellow dolomite, much gypsum, some 

 quartz sand and pyrite. Fumes of sulphur and 

 bituminous matter were given off when heated 

 in closed tube. The dolomite is compact, but 

 in some fragments small round pores, suggest- 

 ing organic origin, were seen. There are scat- 

 tered minute black specks, probably pyrite.. . 155 165 



Red and green shale, dolomitic limestone and gyp- 

 sum. Some gypsum is fibrous, evidently from 

 thjn layers. The sample contains some small 

 pebbles of vein quartz and a few grains of 

 . pyrite. There is also some light gray lime- 

 stone. Heated in closed tube, fumes of sul- 

 phur and bitumen are given off 165 175 



Brownish gray shale and dark gray dolomite, some 

 red or yellowish limestone, considerable gyp- 

 sum, some quartz grains, some pyrite." A small 

 crystal of quartz was noted and a Foraminifer 

 like Textularia globulosa 180 195 



Red shale, dark gray dolomite, and a few frag- 

 ments of red limestone, gypsum, rounded 

 quartz grains, and pyrite. One quartz crystal 

 noted. Fumes of sulphur, bitumen and ammo- 

 nia noted on heating one part of the sample in 

 closed tube. Another sample of the dolomite 

 gave much oil and gave strong fumes of 

 ammonia 165 209 



Gray marly shale, with some fragments of dark 

 dolomite in part impregnated with pyrite, some 

 yellow limestone, gypsum, and a few grains of 

 quartz. Forms like Globiyerina bulloides and 

 Textularia globulosa quite abundant. JBoliv- 

 ina like punctata d'Orbigny noted and a small 

 fragment of a test like Textularia ticrris d'Or- 

 bigny 209 213 



Dark dolomite and yellow limestone, much gyp- 

 sum, some quartz grains, and pyrite. Fumes 

 of sulphur, bitumen and a trace of ammonia 

 noted on heating in closed tube 213 240 



Dark gray dolomite with a little gypsum, and a 

 few grains of quartz and pyrite. Sulphur and 

 bituminous fumes were given off when heated. 

 The dolomite contains more or less angular 

 sand and the dark color is due to pyrite, dis- 

 seminated in very fine cubic crystals. The 

 sample contains Textularia and Globigerina, 

 perhaps from overlying shales. 265 



