474 NEW YORK STATE MUSEUM 



whether it should be classed with the anorthosite or with the gab- 

 bro dikes. But these latter do not seem to be greatly younger than 

 the general mass, and quite likely represent the injection of a por- 

 tion of the mass which had already solidified by material from a yet 

 liquid portion. 



Within the Santanoni quadrangle, next east, local differentiation 

 has produced the masses of titaniferous iron ore of the Lake Sanford 

 and Lake Henderson region. 1 These are well within the anorthosite 

 mass with quite pure anorthosite for the general wall rock, and are 

 remarkable for the narrowness of the gradation zone. No such 

 masses, large or small, have been noted within the Long Lake 

 quadrangle. 



This border gabbro is a rather uniform grained rock, of sufficient 

 coarseness so that the white of the feldspar, the red of the garnet, 

 and the black of the pyroxene, hornblende and magnetite are all 

 prominent. In the less extreme phares of the rock, occasional 

 small uncrushed feldspar cores remain. But the small, glittering, 

 lath-shaped feldspars which are prominent in the less metamor- 

 phosed portions of the gabbros associated with the Long lake 

 gneiss have not been noted in this border rock, and the distinction 

 is believed to be characteristic of the two rocks. 



Anorthosite outliers. Three small outlying masses of anortho- 

 site have been noted within the limits of the quadrangle, and doubt- 

 less there are others which have been missed, or which are covered 

 by glacial deposits. Only masses rather remote from the main body 

 are here under consideration. Curiously all three are in Litchfield 

 park. They are from 4 to 7 miles distant from the main mass, with 

 an intervening broad belt of Grenville rocks. To account for their 

 presence here, and their nonappearance elsewhere is a difficult 

 problem. In but one case do the exposures suffice to give any clue 

 to their relationships to the surrounding rocks. 



The more northerly of the three outliers forms the summit of a 

 small hill which lies between Jenkins and Long ponds. The hill 

 breaks down quite steeply on the north and west in bare rock cliffs, 

 was burned over some years ago, and second growth has not yet 

 gained a foothold on the bare rock, so that exposures are excellent. 

 The hill also forms an easily accessible and excellent viewpoint in 

 all directions but eastward. 



In going north to the hill from the road between Jenkins and 



1 Kemp, J. F U. S. Geol. Sur. 19th An. Rep't, pt 3, p. 409-17. 



