Geology. 



157 



disturbance. . . . The Little Falls fault has a throw of nearly or 

 quite 800 feet at Little Falls." 



One of the most interesting problems suggested by this bulletin 

 is — What is the relation of the so-called Beekmantown forma- 

 tion of this Little Falls region to the true Beekmantown of the 

 Champlain valley ? The author shows how these dolomites over- 

 lap and disappear northward over the Adirondack mass. "Nor 

 does the basal bed at Little Falls appear to represent the real 

 base of the formation, deep well records to the west seeming 

 to indicate an increased thickness in that direction." The 

 sequence of the Upper Cambrian and the succeeding dolomites 

 of the Great Interior Sea apparently denote continuous deposition 

 and show that the dolomites along the south side of the Adiron- 

 dacks are those of a shallow sea, with a sparing fauna. Their 

 age is probably closely connected with the Cambrian and is 

 doubtless older than the Beekmantown of the Lake Champlain 

 area. The faunas of the two areas are widely different, that of 

 the Lake Champlain district being a normal marine one abound- 

 ing in large cephalopods and gastropods, hardly any of which 

 are found in the Mohawk valley. Again, the sequence varies 

 greatly in the two areas, as in the Lake Champlain region the 

 Beekmantown is followed by the Chazy, while in the Mohawk 

 valley the Lowville reposes on the so-called Beekmantown dolo- 

 mites. On the northeast side of the Adirondacks the Paleozoic 

 section is at least 3000 feet thicker than in the Mohawk valley. 



c. s. 



2. 

 pan 



Geology of the WatMns ctncl Elmira Quadrangles, accom- 

 d by a geologic map; by John M. Clarke and D. Dana 

 Luther. Bull. 81, New York State Mus., 1905, pp. 1-29, w T ith 

 a map and a section. — This Bulletin describes in detail the Upper 

 Devonian strata of these quadrangles, with considerable notation 

 of the occurrence of the faunules of the following horizons : 



Chatauquan 



Neodevonian <J 



Senecan < 



Feet. 



Chemung sandstone and shale 800 



Prattsburg shale 250 



High Point sandstone 85 



West Hill flags and shale. ._ 315 



Grimes sandstone 75 



Hatch shale and flags 440 



Rhinestreet black shale 1 



Parrish limestone, in the 



Cashaqua shale 207 



West River shale 35 



Genundewa limestone 1 



Genesee shale 6 -f- 



Much detail is presented in regard to the distribution of the 

 characteristic Naples or black shale fauna and its interlocking 

 but rarely commingling with the eastern or Ithaca fauna. The 

 latter is a direct outgrowth of the Hamilton, as may be seen from 



