JURASSIC. 553 



Jarassic and Cretaceous series of the Sierra de Mazapil and Santa Rosa — Continued. 



Formation. 



Lithologic character 

 and thickness. 



Principal fossils. 



Age. 



Portland. 



01 



p. 



|3 



Kimeridge. 



Whitish marly lime- 

 stones with chert. 



10 meters. 



Perisphinctescfr. koeneni Steuer, 

 P. permulticostatus Steuer, 

 Hoplites cfr. calistoides Behr, 

 H. many species of the group 

 of H. calisto D'Orb. 



of the 

 Berriasen?, 

 Upper 

 Portland. 



Grayish 

 phos- 

 phatic ■ 

 lime- 

 stones. 



(c) Cucullsea 

 horizon. 



(6) Fossiliferous 

 limestones 

 with Peri- 

 sphinctes. 



(o) Limestones 

 with bi- 

 valves. 



Fossiliferous and 

 highly c h e r t y 

 limestones, graj-- 

 ish; black lime- 

 stones; 5-6 me- 

 ters. 



Reddish phosphatic 

 limestones. 



1-2 meters. 



Shales with Waagenia. 



Brownish shaly 

 clays, highly fer- 

 ruginous; 10-30 

 meters. 



Haploceras fialar beds. 



Black compact 

 limestones; 1 me- 

 ter. 



Aucella horizon . 



Brownish shaly 

 limestones, 

 slightly phos- 

 phatic. 



Idoceras beds. 



Shaly clays and 

 marls with lenses 

 and nodules of 

 compact black 

 limestone; 15-30 

 meters. 



Limestones with Neri- 

 nea. 



At the summit a 

 stratum of black 

 and reddish lime- 

 stone with Trigo- 

 nia. The princi- 

 pal mass is ^ay- 

 ish massive lime- 

 stone with inter- 

 bedded gray 

 marls containing 

 bivalvesand beds 

 of coral; of great 

 thickness. 



Perisphinctes santarosanus nob., 

 P. Victoria nob., burkarti nob., 

 Hoplites cfr. rjasanensis Lah., 

 Hoplites cfr. wallichi Gray, 

 Neumayria subrasilis nob. 



Upper and 

 Lower 

 Portland. 



Phylloceras apenninicum Can., 

 Eurynoticeras zitteli nob., 

 Perisphinctes cfr. danubiensis 

 Schlosser, P. nikitini Mich., 

 Virgatites mexicanus nob., 

 Aapidoceras cyclotum (0pp.) 

 Steuer, A. fallax nob., A. phos- 

 phoriticum nob., A. cajense 

 nob., A. zacatecanum ndh. 



Base of the 

 Portland. 



Waagenia cfr. harpephora Font, 

 W. aff. beckeri Neum., W. cfr. 

 knopi Neum., W. cfr. harpe- 

 phora Neum. 



Summit of the 

 Kimeridge. 



Oppelia cfr. trachynota Font. 

 (Oppel), O. aff. strombecki 

 Oppel, Haploceras fialar Op- 

 pel, H. many species, Craspe- 

 dites mazapilensis nob . 



Upper Kimer- 

 idge. 



Aucella, many species of the 

 groups of A. pallasi Keys and 

 A. bronni Rouill. 



Upper Kimer- 

 idge. 



Neumayria profulgens nob., Op- 

 pelia aff. nereus Font., O. flex- 

 uosacostata Qust., Macroce- 

 phalites epigonus nob., Simo- 

 ceras cfr. doublieri D'Orb., 

 Aspidoceras contemporaneum 

 Favre, A. bispinosum Qust., 

 A. cfr. acanthicum Oppel, Ido- 

 ceras laxevolutum Font, I. 

 balderum Oppel, Aulacoste- 

 phanus zacatecanus nob., etc. 



Delimi ting 

 beds b e- 

 tween the 

 lower and 

 upper Kim- 

 eridge. 



Nerinea various species, corals 

 with the marme bivalves 

 (Pholadomya, Trigonia, As- 

 tarte, Opis), gastropoda (Har- 

 pagodes), and brachiopods 

 (Terebratula). At the top of 

 the limestone Simoceras cfr. 

 doublieri Loriol (D'Orb.). 



Upper Juras- 

 sic (proba- 

 bly Sequa- 

 nien). 



