Geology and Mineralogy. 477 



years ago in reporting on the Triassic formation of the Con- 

 necticut valley for the U. S. Geological Survey, as a part of the 

 so-called "main sheet" of trap, locally uplifted on a north-south 

 fault ; although the normal sequence of overlying sandstones with 

 the thin posterior trap sheet was found to the east of the ridge, 

 the underlying sandstones were not then visible at the west base 

 of the ridge. In their absence the thickness of the ridge-making 

 trap sheet could not be determined and its identity with the 

 heavy main sheet in other ridges to the south and west remained 

 to that extent uncertain. 



In later years a large quarry, conspicuously visible from the 

 main railroad line near Newington station about a mile away, 

 has been opened in the west face of Cedar mountain ; the trap is 

 thus laid bare for about a quarter-mile north and south in three 

 great excavations. The northern quarry has its floor about 20 

 feet above the drift-covered low land to the west ; no underlying 

 sandstone is there exposed. The middle quarry is cut down to 

 the lowland level, and the underlying red sandstone, dipping 

 eastward about 20 degrees, is well exposed in its southwestern 

 part to a thickness of 10 or 15 feet ; at the contact of sandstone 

 and trap, the trap is dense and much finer grained than in the 

 greater part of the quarry face ; and the sandstone is indurated 

 and jaspery for a foot or two below ; the bedding is hardly dis- 

 turbed. The southern quarry has its floor about 50 feet above 

 the lowland ; here the sandstone is laid bare, with a steep glaci- 

 ated face, between two rock-crusher buildings ; also at the south- 

 ern entrance to the quarry, but no contact with the trap is visible. 



The thickness of the trap sheet is thus limited underneath at 

 a measure that is closely comparable with the thickness found 

 elsewhere. On crossing the trap ridge to the east, a ravine fol- 

 lowed by a road was seen to enter it obliquely from the north, 

 probably a consequence of a branch fault ; farther down on the 

 eastern slope, no sandstone could be discovered in contact with 

 the upper surface of the trap sheet; but the stone walls con- 

 tained a good number of blocks composed of grayish sandstone 

 containing fragments of vesicular trap, such as characterizes the 

 sandstone at overlying contacts on the back slope of the main 

 sheet in other ridges, which are thereby proved to be extrusive 

 lava flows. The identification of Cedar mountain as an 

 upfaulted part of the main trap sheet is thus supported. 



3. Canada, Department of Mines. — The following list con- 

 tains the titles of recent publications of the Canadian Depart- 

 ment of Mines. (See vol. 44. pp. 81-83.) 



(1.) Geological Survey Branch; William McInnes, Direct- 

 ing Geologist. 



Memoirs. — No. 84. An exploration of the Tazin and Taltson 

 rivers, North West Territories ; by Charles Camsell. Pp. 124, 

 1 map, 18 pis. 



No. 87. Geology of a portion of the Flathead Coal area, 



