534 



Report of the State Geologist. 



which occur in these gneisses are often surrounded by rims of titantite, 

 indicating that they are titaniferous, and this is frequently the case in these 

 gneisses throughout the whole region. 



The facility with which gabbro grades into diorite has been shown by 

 several observers. These hornblende gneisses of the Adirondack* seem also 

 to grade into gabbro-gneisses w hose igneous origin and relationship with the 

 greater gabbro masses are regarded as certain, and it is quite probable that the 

 hornblende-gneisses will prove to be merely a phase of them. 



Series //and /// are not known to occur in the township, though it is 

 quite likely that basic gabbros may be found in the gneisses. 



Series IV. All the northeastern half of the township is occupied by 

 the Potsdam sandstone, with prevailing dips of from 5° to 10° to the N. W. 

 The striking feature of the Ellenburgh Potsdam is its coarseness, even at 

 considerable distances from the gneiss, so that heavy conglomerates here 

 range through a thickness of 200 feet or more. A quarter of a mile west of 

 Star post office, and 200 yards south of the road, the Potsdam is found within 

 fifteen yards of the gneiss, a slight depression with no rocks exposed lying 

 between. The Potsdam is not as coarse as might be expected so close to the 

 contact, no coarser in fact than is the larger part of the formation in the town- 

 ship. This, together with the somewhat abnormal dip of the sandstone at 

 this place, gives rise to the suspicion of a north and south fault here (the 

 Potsdam lies to the east of the gneiss), and such a fault would explain the 

 sudden shoot to the north which the gneiss takes along this line. 



In addition to the prevailing coarseness, much of the rock is very feld- 

 spathic, as is the case throughout the county in the basal Potsdam. The 

 less coarse, rapidly disintegrating, hematitic beds which frequently accompany 

 the conglomerates make, however, little show in this township. But there is 

 often a rapid alternation of coarse and finer beds, giving a thin-bedded 

 character to much of the coarse rock. 



In the extreme northeast the conglomerates are left behind, and the rock 

 consists almost wholly <>f quartz sand. Yet even here certain horizons are 

 very pebbly. A very interesting exposure of the sort occurs in the bed of the 

 English river at Ellenburgh depot. The dip here is slight and the surface of 

 a single layer is exposed over many square yards. The rock is a coarse, even- 

 grained grit but is set with numerous pebbles of white quartz, sometimes 

 over two inches in diameter. The horizon is w ell above the base and affords a 

 good instance of the coarse character which the rock holds throughout. In 

 addition to the quartz ]>el>Mes three Larger rounded masses of sandstone, from 



