220 AMADEUS W. GRABAU 
sively higher beds appear beneath the quartzite in the direction 
of the retreat, indicating continuous deposition during the slow 
regressive movement of the sea, this being checked as the localities 
successively emerged. 
A widespread negative diastrophic movement is thus shown to 
have taken place over the whole of the North American continent, 
accompanied and followed by the spread of subaérial clastics over 
most of the area.. At least 2,500 feet of calcareous strata were 
deposited in the non-emerging areas, and most of this constitutes 
the depositional equivalent of the retreatal movement (see map, 
igs 3): 
The Beekmantown faunas.—The Beekmantown faunas are, so 
far, best known from the Lake Champlain region, the Mingen 
Islands, and the Newfoundland section. The Lake Champlain 
region, including the Phillipsburg section of the Canadian exten- 
sion, has furnished a considerable number of species. Its distinctive 
character will be seen on consulting published lists. 
The Pogonip limestone of Nevada contains mostly species un- 
known outside of this formation in the West, though a number of 
them have been referred by Walcott to eastern species, largely Tren- 
ton and Chazy types. In almost all such cases, however, the identi- 
fication is provisional, and regarded by Walcott himself as doubtful. 
There is nothing in the character of the fauna which positively 
demands its reference to either the Chazy or Trenton, as has been 
done. 
GRAPTOLITE FACIES OF THE BEEKMANTOWNIAN 
In the Hudson and St. Lawrence valleys the Beekmantown is 
represented by the lower portion of the Hudson River shales, above 
the beds with Dictyonema flabellijormis. Some 340 feet of strata 
appears to be referable to this series, of which the lower 300 feet 
constitutes the first and second Deepkill zones, synchronous with the 
Upper Point Levis zone of Canada and the St. Anne zone of New- . 
foundland. Here the genera Chlonograptus, Goniograptus, Tetra- 
graptus, and Phyllograptus (P. anna), with Didymograptus bifidus, 
characterize a succession of zones recognizable in various parts of 
the world. The upper forty feet of this series (third Deepkill zone) 
