lOO STRATIGRAPHICAL GEOLOGY. 



to the outlier of porphyritic gneiss near Wing Road station. There seems 

 to be an antichnal axis on the west flank of Mt. Lafayette, and hence 

 the two areas may be connected by a syncHnal beneath the Bethlehem 

 gneiss in Franconia and Bethlehem. The following are the facts sug- 

 gesting the existence of the anticlinal. We have no observations of the 

 dip north of the outlet of Echo lake. On Bald mountain, a hill north- 

 west from Echo lake, the dip is from fifty to sixty degrees north-westerly, 

 verging northerly. The rock is coarse; the porphyritic crystals are 

 larger than is common; the mica is black; and the inclination was ob- 

 served very satisfactorily. Dykes of trap cut across the hill. The cliffs 

 on the north and east sides of Echo lake are composed of porphyritic 

 gneiss dipping about 50° N. 32° W. It is supposed that this rock is 

 continuous to the Lake of the Clouds, north of Eagle cliff, but, on ac- 

 count of the difficult travelling, the actual connection has not been traced 

 out. The ragged cliffs between the Echo and Cloud lakes are conceived 

 to belong to the Franconia breccia, which is an igneous overflow consist- 

 ing of large fragments torn off from the porphyritic rock, and embedded 

 in a feldspathic paste. At the Lake of the Clouds no doubt exists as to 

 the occurrence of the porphyritic gneiss ; and I have the impression that 

 the feldspar crystals lie in horizontal planes, but I cannot be absolutely 

 certain of it. I have noted that the rock makes its appearance half-way 

 between the crest of Eagle cliff, where the new path crosses it, and the 

 lakes, and that the strike may be N. 28° E. both east and west of these 

 small tarns. Physically sj^eaking, there is a broad shelf where this water 

 is situated, which is more than four thousand feet above the sea, from 

 whence water flows northerly and southerly. Following the old bridle- 

 path from the Cloud lakes to the south, the porphyritic gneiss crops out 

 about one third of the way down, with a dip of fifty degrees easterly. 

 To the east of the lakes towards Lafayette a finer-grained gneiss suc- 

 ceeds, which may correspond to one of the overlying formations. I think 

 the dip is easterly in this case. There seem to be outcrops of this rock, 

 also, on the cast side of the mountain underneath the Lakes of the 

 Clouds. Thus, although the facts observed respecting the dips are 

 meagre, the easterly and westerly inclinations are clearly known to exist 

 in the proper place to constitute the anticlinal ridge represented upon 

 Plate VL 



