422 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



vol.. XXVI. 



COMPOSITE SECTION OF THE LOWER DEVONIC AND ONTARIO OF 



MARYLAND. 



The Marcellus stage of the Middle Devonic rests directly upon the 

 eroded Oriskanian. No Esopus, Schoharie, or Onondao-a deposits 

 occur in Maryland or farther south. 



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DESCRIPTIONS OK HORIZONS 



la. Heavy-bedded arenaceious limestone, gradually changing downward into a 

 black chert or siliceous shale. In the lowest beds are found Spirifer cum- 

 berlandix, S. concinnoides, and Eatonia sinuata. Fossils, however, are rare 

 until 100 feet above the base of this division, where the characterizing 

 Hipparionijx fauna attains greater individual and specific representation, 

 culminating in the upper 100 feet, the present source for nearly all of the 

 Cumberland Oriskanian fossils 258 feet. 



16. Bedded and nodular black chert and siliceous shale, with a sparse fauna 

 distinct from the Hipparmiyx fauna above and from the Helderbergian 



below 90 feet. 



Near the base are found Anoplothcca Jlabellites, Lcptostruplda arctimus- 

 cula, and Ostracoda. Just below the middle occur A. flahcUitcs, Spirifer 

 tribuHs, S. paucicostata, Beachia suessana immatiira, Anoplia nuclcata, 

 Pholidopii multilamellosa, Tentaculttes acula, and Diaphorosloma desmatam. 

 Near the top is an abundance of Ostracoda and C'honetes hudsonica. 



(In western Maryland the Becraft is not present or is not normally 

 developed. Ninety miles east occur the following beds, completing the 

 interval:) 



Dark blue arenaceous limestone, with lumps of black chert. The fauna is 

 most abundant in the upper half, where Renssdxria xquiradiata is the 



characteristic fossil. No Spirifer macropleura occur here about S.5 feet. 



Other fossils arc Rhipidoinella assimilis, RhynchoneUa cmhiens, large 

 Eatonia medialis, small A. flabellites, Spirifer cyclopterus, S. concirmus, 

 Cyrtina rostrata, etc. 



:g 03 

 W.S 



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(The remainder of the section is complete in western Maryland.) 

 '2b. Soft, bluish argillaceous shales, with some harder layers and occasional 

 manganese-phosphatic nodules; Chonefes heldcrbergi.r Rowe, Meristella 

 arcuata, Trematospira multistriata. Spirifer macropleura, Orthothetes wool- 



worthanus, Stropheodonta becki, etc 20 feet. 



2c. Massive gray limestone, with bands of chert, becoming thin-bedded above, 



with partings of shale; characterized by Spirifer macropleura 44 feet. 



The fauna can be collected to better advantage around Cumberland. 

 Some of the .species are Edriocrinus poeilliformis, Dalmanclla perelegans, 

 Rhipidomella oblata, Eatonia singularis, E. peculiaris, E, medialis, Anoplo- 

 theca concava, Trematospira midtistriata, Rarazyga deweyi, Spirifer perlamel- 

 losus, S. macropleura, S. cyclopterus, Platyceras spirale, Phncops logani, etc. 



.3«. Massive, regularly bedded, blue-gray limestone. It is the prominent ridge 

 of the "Devils Back Bone," near Cumberland. At the top are found 

 typical Gypidula galcufa, Spirifer cyclopterus, and stems of Lepadocri- 

 n'ls 16 feet. 



36. Shaly limestone without fo.ssils 1 foot inches. 



3c. Massive, regularly bedded, blue-gray, unfossiliferous limestone 22 feet. 



3d. Heavy-bedded nodular limestone, filled with Stromatopora (locally known 



as the first Stromatopora bed) 7 feet 6 inches. 



3e. Heavy-bedded blue limestone, almost without Stromatopora 25 feet. 



•r" S OS 



