Gregory] TESCHENITES. 117 
dense forest growth, and, when the moss and vegetable debris is 
removed, show their glacial grooving in a very fresh state. This large 
dike can not be traced to the east, but forms the hill immediately west 
of the road, and was found outcropping on lot 106, nearly a mile to 
the west. Forest and swamp prevented further exploration. 
The large hill on lot 107 is another teschenite mass, which extends a 
half mile to the east and is terminated by two small knobs on lot 100. 
The ledges best exposed are on the northeast corner of the hill, where 
they present a ragged ridge about 200 feet wide, which probably indi- 
cates the dike. This dike is separated from the one first mentioned by 
the sandy slates of the region. 
On lot 106 the field relations of the teschenite are seen to the best 
advantage, for here the land has been cleared and plowed and a section 
running for a long distance directly across the strike can be examined. 
Here the large dike traced from the east is seen to take on a rude 
columnar form at the contact, with columns perpendicular to the wall, 
and it is seen to be sheared in a direction rudely parallel with the slate 
bedding. Teschenite dikes and the slates alternate along the whole 
section. The dikes have black, dense border facies and coarse crys- 
talline interiors, and contain many broken and hardened fragments of 
slates. The slates have a general strike N. 50° E. and dip SE. <60°, 
and are much folded and broken near the teschenites. In general the 
dikes follow the direction of the strike, but those taking other direc- 
tions are also present. 
Besides this Mapleton area the teschenite outcrops on the State road 
at the southwest base of Castle Hill, but the extent and character of 
its occurrence at that point have not been studied. 
