652 E. O. ULRICH REVISION OF THE PALEOZOIC SYSTEMS 



The second represents the shale facies, which is typically developed in 

 the Levis channel of Ulrich and Schnchert. Its fauna is almost totally 

 different from that of the limestones of this period, being composed 

 chiefly of graptolites that, with very few exceptions, are entirely wanting 

 in the limestone facies. The graptolites are found in several zones, each 

 of which is marked by diagnostic species. As commonly designated, these 

 zones from below upward are as follows : ( 1 ) Dictyonema flabellif orme 

 zone, (2) Tetragraptus zone, with two subzones — Clonograptus or lower 

 Tetragraptus bed and Dichograptus bed — and (3) Didymograptus bifidus 

 or Phyllograptus typus zone, which doubtless includes distinguishable 

 subzones. Ruedemann discovered the first of these zones in a basal part 

 of the Levis shale exposed at the falls of Hoosic River at Schaghticoke, 

 New York. He also found and published the section in Deepkill, near 

 Grant Hollow, Rensselaer County, New York, which includes the second 

 and third zones besides an overlying "Diplograptus dentatus zone,'' 

 which may be younger than Canadian. All of these graptolite faunas are 

 fully described, and their stratigraphic relations discussed, by Ruede- 

 mann in papers published by the New York State Museum, notably in 

 Memoir 7, 1905. The shale facies and the graptolite faunas are further 

 discussed beginning page 674. 



The third or Newfoundland facies consists chiefly of limestones — con- 

 stituting Divisions F (500 feet), G (400 feet), and H (265 feet) of 

 Logan's section — ^which contain, besides a much larger number of 

 localized species, just about enough Beekmantown fossils (according to 

 Billings 12 out of 62) to make it reasonably certain that these widely 

 separated limestones are approximately contemporaneous and certainly 

 of the same period. The general composition of this Newfoundland 

 fauna, especially of Division G, is more closely simulated by the Cana- 

 dian fauna in Oklahoma and western Texas than by any in the Beek- 

 mantown limestone. 



The Beehmantoivn in Maryland and southeast Pennsylvania. — Two 

 sections showing the general composition of the Beekmantown lime- 

 stone in the Maryland basin of the Appalachian Yalley, also provis- 

 ional faunal lists, have recently been published in Folio 170, Mercers- 

 burg-Chambersburg, Pennsylvania, quadrangles, by the TJ. S. Geological 

 Survey. They illustrate, also, the lithologic changes taking place in the 

 formation in an east-west direction across the strike. In the eastern belt 

 fully three-fourths of the 2,265 to 2,400 feet of thickness consist of 

 nearly pure limestone; in the western band more than half of its 2,310 

 feet is more or less highly magnesian. However, the Stonehenge member 



