CAMBRIAN CORDII,IvER^\N SEICTIONS — WALCOTT 201 



Feet 



3a. IMassive bedded, gray, arenaceous cliff- forming limestones 675 



3&. Thin-bedded, gray limestone and sandstone, with small lentiles 

 of light-gray limestone. The irregular arenaceous portions 

 weather buff and form a buff band where the reck is in the 

 cliffs 75 



3c. Massive bedded, light gray, arenaceous limestone, with thinner 

 bedded, purer limestones at intervals. On the mountain 

 slopes the massive beds form cliffs, and the thin-bedded more 

 shaly portion forms slopes 245 



Sd. Massive bedded, light gra}-, arenaceous limestone, with some- 

 what purer, slightly banded limestones toward the top 175 



Se. Massive bedded light gray, banded limestones, that break up 



into thin and often shaly layers on exposure to the weather. 51 



3/^. Massive bedded, light gray, arenaceous limestones 164 



Total of Silurian ? 1,385 



The line drawn between the Cambrian and the Silurian is based 

 largely on the change in the character of the limestone, from the 

 coarse, gray, arenaceous limestone to a much purer, gray limestone, 

 and the occurrence, about 150 feet from the top, of fragments of a 

 species of Ptychoparia. 



CAMBRIAN 



LIMESTONE: 



Feet 



la. Massive bedded, hard, gray and bluish gray limestones that 

 break up into thin, irregular layers on exposure to the 

 weather. The color of many thin layers and the thick layers 

 on their bedding planes is yellow to buff. The upper 100 feet 

 contain massive dove-colored limestones and near the top a 



few feet of siliceous limestone 550 



Fragments of a species of Ptychoparia were noted about 150 

 feet below the summit. 



lb. Greenish and gray, thin-bedded limestone, with some arena- 

 ceous shale and thin layers of greenish sandstone in the shale 90 

 Numerous annelid trails and fragments of trilobites occur 

 throughout. 



If. Massive bedded, gray limestone that breaks up into thin, 

 irregular layers, in very much the same manner as the Pil- 

 grim limestone, but is usually more massive. It is quite 

 arenaceous near the central portions, where it is more mas- 

 sive bedded for a short distance 680 



One hundred and seventy feet from the top there is a band of 

 thin-bedded oolitic limestone, in which fragments of trilo- 

 bites are numerous ; also a small Obolus-Wke. shell. Oolitic 

 limestone, interbedded with irregular, thin-bedded, bluish 

 gray limestones, occurs in the lower 170 feet. 



Total of limestone 1,320 



