598 



Report of the State Geologist. 



The former has been the case with the lake Champlain basin and 

 apparently with its arm up through Crown Point and PenfiehTs pond 

 into western Ticonderoga, along the easterly branch of Putnam's brook (see 

 map of Ticonderoga, Report of the State Geologist of New York for 1898, 

 p. 452) ; with the lake George basin and its arm up through the Trout Brook 

 valley in Ticonderoga (see last reference), and in the Hudson - Schroon 

 valley, we have doubtless still [(reserved for us the old Cambrian-Ordovician 

 topography. It is furthermore a curious fact that the strike of all these out- 

 liers is northeast, and the dip is also low to the northwest. It is remarkable 

 that the same strike and dip hold good for the embay men ts of these rocks all 

 along the west shore of lake Champlain, in Essex county, and notwithstanding 

 the minor faulting we cannot well avoid inferring that there has been con- 

 siderable tilting in which the county to the east and southeast has risen. 

 The Green mountain upheaval may in part account for this, but the Schroon 

 outlier is a long way into the Adirondack^ to have felt its effects, when it 

 produced such slight tilting along lake Champlain itself, only twenty miles 

 aAvay from the principal elevation. If we assume anticlinal folds instead of 

 faults, it is extraordinary that the eastern limbs should be eroded while the 

 western remain. Tilting in blocks with fault lines approximately parallel 

 to the present valleys, is more likely to be the true explanation.* 



It is also worthy of remark that the Schroon valley is a base-leveled one, 

 or nearly so, except as concerns side tributaries. The Schroon itself is a very 

 sluggish stream for a mountainous one, and the fall is very slight, as was 

 noted above under North Hudson, from its source to Schroon lake. Such 

 obstructions as it is now at work upon are chiefly glacial deposits. The great 

 geologic age of the valley no doubt accounts for this sluggishness and the 

 question may be raised if other slow streams, not evidently held in abeyance 

 by glacial deposits, may not be explained in the same way. 



Series V. Several dikes have been noted. The point on Pharaoh pond, 

 where No. 70 is located, is well provided with them, as the accompanying 

 sketch (Figure 1) shows. The laminations of the gneiss run straight across 

 the strike of the dikes. The dikes have also proved an easier prey to the 

 weathering effects than has the gneiss and the retreat of the shore along their 

 lines has in part at least caused the points. The dikes cut pegmatite veins, 

 and in one case a small dike cuts a larger one. The occurrence of these little 

 scraps of igneous rock in doubly terminated fissures and running like veinlets 



* Since itae above was written, topographic maps of this area have been issued by the United States Geological Survey, and 

 based on these, the writer has discussed this question at greater length in the " Bulletin of the Geological Society of America," - 

 Vol. VIII.. p. 408, Plate 51. 



