324 MESOZOIC FLORAS OF UNITED STATES. 



Feet. 



10. Shale bed (or days) below the cycad level ~ 35 



9. A layer of light-colored sandstone 12 



8. Sandy shaly material 30 



7. Sandstone 60 



6. Shale much like No. 3 65 



Nos. 3-6 make a somewhat homogeneous series about 125 feet in thickness. 



5. Same shale in character as that seen just below (4) 2 



4. Sandstone breaking up into large blocks 6 



3. Shale with nodular layers followed by very shalj' material 45 



2. Marine Jurassic (Belemnite horizon) 125 



1. Red beds. 



The preceding section may be supplemented b.y the following briefer 

 one, introduced merely to explain in a general way the continuation of 

 the thus far barren horizons, save for silicified wood, here forming the 

 summit of the rim: 



Section at Parkers Peak, rising 200 feet atove the cycad horizon and about 100 feet above Matties Peak. 



Feet. 

 4. A highh^ characteristic quartzitic cap, forming, through its peculiar erosion about the head of Hells 



Canj'on, 2 miles east of the peak, picturesque pine-clad mesas 80 



3. Softer sandstones, mostly talus-covered; basal portions form mesas east of Parkers Peak 50 



2. Soft flesh-colored sand rock (pinkish or whitish ), forming cliff 50 



1. There should follow closely the red and yellow rock, followed beneath by the blue shale, between 



which two horizons are many of the cycads. At the head of the trail, 2 miles east of Arnold's 



ranch there is a distinct blue clay contact with the yellow cycad sandstone, and much silicified 



wood is present. 



There is occasional fossil wood on the tables mentioned in No. 3, 

 and there is a presumption that they correspond to certain high tables 

 on the southern side of "Calico Can3^on," which are about 100 feet below 

 No. 31 of that section and bear large quantities of silicified logs. 



In conclusion, I give a section from the extreme northern hills, 

 obtained at the office of the Aladdin (formerly Barrett) Coal Company, 

 and called by them the Bore Hole B section. Being the result of a boring, 

 it is most interesting to compare this section with that given b}^ Mr. 

 Walter P. Jenney on page 582 of Ward's Cretaceous Formation of the 

 Black Hills. These sections are from the same point, Jenney's being 

 the result of a surface examination of the finely exposed rim escarpment, 

 and this section the record of a boring. Whoever will take the pains to 

 compare these two sections will realize how difficult it is to correlate and 

 reconcile the sections of different observers in the case of a highly 

 developed series of sedimentary rocks like that of the Black Hills rim in 

 the absence of positively identified fossils collected with care from horizons 



