148 The Lower Devonian Deposits of Maryland 



ridge. The cutting of the Huntington Division of the Pennsylvania Kail- 

 road has aided greatly in exposing this section. The Keyser at this point 

 consists of fairly pure limestone and there is little talus. The strata stand 

 in practically a vertical position, making the measurement of the section 

 comparatively easy. The lower strata of the Keyser are heavy-bedded 

 carrying but few fossils, chiefly small Camarotoechia and ostracods. The 

 succeeding 35 feet are sparsely fossiliferous. Above this, bryozoa and 

 Chonetes jerseyensis are found, immediately overlying which is the lower 

 crinoid bed, 5 feet in thickness. One hundred and thirty to 137 feet above 

 the base of the Keyser occurs the Gypidula coeymanensis var. prognostica 

 zone, 7 feet in thickness, abounding in that form. Immediately beneath the 

 Gypidula zone the following forms are found which are the same as those 

 occurring in a similar position in the heavy-bedded blue limestone at the 

 Market Street Bridge section in the city of Cumberland: Merista typa, 

 Dalmanella concinna, Chonetes jerseyensis, Spirifer modestus, S. van- 

 uxemi, Strophonella geniculata, Halysites catenulatus. Schuchertella 

 deformis and 8. deckerensis are found above the Gypidula zone, other 

 species occurring less frequently. The prolific bryozoan fauna which is 

 characteristic of the middle Keyser of the Cumberland area is found 140- 

 156 feet above the base of the section, above which the limestone becomes 

 lieavy-bedded carrying Atrypa reticularis and Leptcena rliomhoidalis. 

 The upper part of the Keyser contains two heavy beds of stromatoporoids 

 and terminates above in thin-bedded, banded, limestone which is sparingly 

 fossiliferous and constitutes the Leperditia alta zone. The contact of the 

 Keyser and Coeymans is admirably shown.^ 



Heldekbeeg Formatio:^ 



„ ,, , Vertical Total 



Coeymans Memoer thickness vertical 



feet thickness 

 Massive crinoidal limestone forming main ridge of Devil's 

 Backbone. At its base are limestone pebbles 6.0 .... 



Keyser Memher 



Thin-bedded to shaly limestone 2.7 289.6 



Stromatopora bed 0.7 286.9 



^ The figures after the names of fossils indicate the altitude in feet at which 

 they occur above the base of the formation. 



