Mahylaxd Geolooical Survey 53 



Oriskany formation; the Middle Devonian is divided into the Eomney 

 formation made up of the Marcellus and Hamilton members; while the 

 Upper Devonian consists of the Jennings formation composed of the 

 Genesee, Portage, and Chemung member?, and the Hampshire formation. 

 This report was accompanied by a new geological and agricultural soil 

 map of the State bearing date of 1907, on which the distribution of the 

 Devonian formations, viz., Helderberg, Oriskany, Eomney, Jennings, 

 and Hampshire is shown. 



Dr. C. K. Swartz published a preliminary article on " The Ithaca 

 Fauna in Maryland " in 1907 which was followed in 1908 by a more ex- 

 tended one on the succession of faunas in the Portage and Chemung for- 

 mations of Maryland. These two papers contain the first account of the 

 Ithaca fauna in Maryland which, together with the subjacent Naples 

 fauna, occurs in the Portage member of the Jennings formation. 



In the Mercersburg-Chambersburg Folio of the U. S. Geological Survey, 

 published in 1910, the area in Pennsylvania just to the north of Wash- 

 ington County, Maiyland, is described by George W. Stose. The Helder- 

 berg limestone is considered the youngest formation of the Silurian 

 System which is shown in the southwestern part of the Mercersburg quad- 

 rangle, the one located directly northeast of the Hancock quadrangle. 

 From this area certain species of fossils are listed which " are referred to 

 the Coeymans ('Lower Pentamerus '") horizon of the Helderberg lime- 

 stone of New York," while from the upper part of the limestone other 

 species were obtained which are stated to be " undoubtedly a New Scot- 

 land ('Delthyris shaly limestone') fauna." Furthermore it was stated 

 that " A Becraft fauna was also found in this formation in the Hancock 

 quadrangle by the Maryland Geological Survey, so that correlation of the 

 formation as a whole with the New York Helderberg is positively es- 

 tablished." ' 



Under the Devonian System it is stated that " Few outcrops of the 

 Oriskany formation are present m the Mercersburg quadrangle," from 

 which but three Oriskany species were reported and from just outside 

 (west) of the quadrangle eight additional ones, and this is stated to be 



^Loc. cit.. Field Edition, p. 86. 



