OUTLINE OF THE GEOLOGY OF MORIAII 



331 



Brief description of the map. The accompanying map has 

 been roughly reproduced from advance sheets of the U. S. Geologi- 

 cal Survey and from the County Atlas of Essex Co. Only the 100 

 foot contours are given, to avoid confusion of lines. While not 

 claiming to be more than a general picture of the topography, it 

 does show the elevations with all the accuracy needed for a first 

 draft and as such has been employed. In the subdivision it has been 

 the endeavor to show the areas occupied by the gneiss, the crystal- 

 line limestones, the outlying gabbros, the main anorthosite masses, 

 the Potsdam sandstone and the Lower Silurian limestones. Where 

 all rocks are concealed by drift, this has its appropriate sign. Prac- 

 tically all the roads were traversed in Moriah and Westport and a 

 corner of Elizabethtown. The only omitted area is a small one in 

 the extreme northwest of Moriah.* But it is recognized that some 

 outlying gabbro areas may have been overlooked, although all acces- 

 sible hills were climbed. On many the forest growth and smaller 

 vegetation conceal all exposures. Some gneissoid forms of anortho- 

 sites may be included in the areas drawn as gneiss, for as already 

 remarked the intermediate varieties are extremely hard to classify, 

 even when the prominent types are readily recognized. The geolog- 

 ical sections will serve to indicate the stratigraphical relations in sev- 

 eral places. 



OUTLINE OF THE GEOLOGY OF MORIAH 

 An examination of the accompanying map will show that the 

 gneisses with iron ores make up the greater part of Moriah. There 

 is also a belt of crystalline limestone and black schist in Port Henry 

 and another east of Ensign Pond. Along the Lake Champlain front 

 the Potsdam sandstone is well developed, and the Calciferous shows 

 in one small spot just north of Port Henry. The later sediments 

 although present in the townships on the north and south are absent 

 in Moriah. The anorthosites appear in the southwest and form one 

 especially high hill, Harris Hill, and several others, hardly inferior. 



Outlying masses of gabbros are frequent and often strongly gneis- 

 soid. A great sheet of gabbro has been cut by drill cores near Mt Bob, 

 Mineville, and an enormous mass of it underlies the Cheever Mine, out- 

 cropping all along the lake. Another great sheet, at least 250 ft thick 

 forms the middle (horizontal) third of Bald Peak. Several diabase 

 (dikes have also been met. Geological sections accompany the map. 



* Since filled from observations made in 1894. 



