450 REPORT ON NATIONAL MUSEUM, 1886. 



Triassic stones. Clay-boles abound in some portions of the rock, but 

 can be avoided by careful selection. The stone is not at all sbaley and 

 shows little, if any, disposition to scale when exposed to the weather. 

 The Suiithsouiau Institution, erected in 1848-54 from this stone, sliows 

 few defects Irom weathering alone, and these only in those cases where 

 they might have been avoided by judicious selection. Ou blocks of 

 this stone in the aqueduct of the Chesapeake and Chio Canal which 

 have been constantly permeated by water every season for fifty yeiirs, 

 the tool-marks are still fresh and no signs of scaling arc visible otlier 

 than are produced by too close contact at the joints. The quarries are 

 conveniently situated near by the canal, where stone can be readily 

 loaded upon boats for the Washington markets, from whence it can be 

 shipped by rail or vessel to all our principal cities. 



Massachusetts. — The beds of Triassic sandstone, which furnish in Con- 

 necticut the well-known Portland brownstone, are continued up the 

 valley of the Connecticut Kiver to the northern boundary of Massachu- 

 setts and furnish in several places valuable deposits of building mate- 

 rial. At East Long Meadow, in Hampton County, quarries are worked 

 in this formation which produce a rather finer grained stone than that 

 of Portland and of a bright brick-red color. Like all the Triassic stones 

 it is soft and works readily, and on account of its warmth of color can 

 be used with very pleasing effects in a variety of combinations. 



The extensive formation of Primordial conglomerate in Dorchester, 

 Koxbury, Brookline, and other towns south and west of Boston furnishes 

 an inexhaustible supply of durable building material for rough work, 

 but which, owing to its coarseness, is unsuited for ornamental work of 

 any kind. The stone is quite variable in different localities, but may, aa 

 a whole, be said to consist of a greenish gray groundmass or paste in 

 which are imbedded rounded pebbles of all sizes up to several inches 

 in diameter of quartz, granite, melaphyre, felsite, and a variety of rocks. 

 Tliis composition renders the smooth dressing of the stone a practical 

 impossibility', and it is used only in the rough state, advantage being 

 taken of the numerous joint faces, which in building are placed outward, 

 thus forming a comparatively smooth wall. The stone thus forms a 

 very durable building material and has been used with good effect in 

 several churches and other buildings in and about Boston. 



Michigan. — According to Professor Conover* the beds of Potsdam 

 sandstone occurring with frequent outcrops in the northern part of the 

 Upper Peninsula in this State are likely to furnish the largest quantity 

 and the best quality of building material found within the State limits. 

 The stone quarried from this formation at Marquette is of medium fine- 

 ness of texture, of a light brownish -red color, often curiously spotted or 

 mottled with gray. These gray spots are generally rounded and \'ary 

 in size, according to Mr. Batchen, from that of a pea to 12 or 18 inches 

 in diameter. These blotched portions are usually rejected in building, 

 * Report Tenth Census, 1«80, p. 2'->7, 



