REPORT OF TH1 DIRECTOR AND STATF < ; t".< >l.<)< i I ST 



r67 



age are the surface rocks over a considerable tract, they are effect- 

 ively concealed by heavy drift except at West ("hazy, where a 

 thickness of 10 feet of massive. blue-gray dolomite is exposed in 

 the river and a higher layer at the surface in the town. South of 

 West ("hazy ant 1 cast of Kami hill there is not a single exposure 

 of rock within the limits of the map. though plentiful outcrops 

 occur in Beekmantown. just beyond those limits. Some uncer- 

 tainty therefore prevails as to just what is underneath. It is 

 the writer's opinion that the Calciferous extends all the way to 

 the edge of the Rand hill, being there faulted down against the 

 pre-Cambrian. This opinion is based on the fact that to the south, 

 in Plattsburg. the Calciferous runs as far west as what is taken 

 to be the prolongation of this fault line. But it is by no means 

 impossible that another fault is concealed in this interval, 

 in which case Potsdam would lie between the Caciferous and the 

 pre-Cambrian. On account of this uncertainty the concealed in- 

 terval is colored as Pleistocene on the map. such coloration being 

 used only where the Pleistocene deposits are sufficiently exten- 

 sive to render the areal mapping of the older rocks at all doubt- 

 ful. 



The Calciferous formation is a quite thick one in the Champlain 

 valley. Brainard and Seeley having shown a thickness of 1800 feet 

 in western Vermont. No complete section has been found in 

 New York, but the different parts of the formation show much 

 the same thickne.-cs as in Vermont, and the total thickness can not 

 fall greatly short of the amount found there. The meager ex- 

 posures at West Chazy do not suffice for the determination of the 

 precise horizon in the formation. They lie close to a fault line, 

 dip 5 C to the east instead of in the usual northerly direction and 

 may represent a small dislocated block produced by the faulting. 



Chazy limestone. Only the extreme lower beds of this forma- 

 tion are shown within the map limits, occupying a narrow zone 

 between two great faults, between which the Chazy is thrown 

 down. The dip is away from the westerly and toward the east- 

 erly fault. The extreme base is not shown, but the lowest layer 

 appearing is a light colored, calcareous sandstone which seems 



