646 THE JOURNAL OF GEOLOGY. 



microscopic and chemical characteristics and mode of occurrence are briefly 

 described. The following theories, proposed by others to account for the 

 peculiar markings, Mr. Thompson considers inadequate : (1) Escape of 

 imprisoned air ; (2) gaseous emanations ; (3) infiltration of dark mineral 

 matter ; (4) shrinkage of the stone. He thinks they are due to interbedded 

 layers of vegetable matter. Experiments were made to reproduce the char- 

 acteristics of the landscape marble, and an imaginative word-picture is drawn 

 of the conditions under which the writer supposes the stone to have been 

 formed. T. C. H. 



The Famous Connecticut Brownstone. By Burton H. Allbee (Stone, 

 Vol. IX., No. 1, June, 1894, pp. 1-31). 



The famous Connecticut brownstone quarries at Portland have been 

 operated for more than 200 years, and at the present time are worked on a 

 gigantic scale. Mention is made of these quarries in the official records of 

 Middletown, September 4, 1665, and in 1690 six acres were sold to the town 

 by the Middlesex Quarry Co. The quarrying is done at present by three 

 companies, who utilize more than 1,000 acres, and employ 1,000 to 1,200 

 men. The annual production varies from 1,700,000 to 2,000,000 cubic 

 feet, half of which is high-grade dimension stone and the remainder used 

 for piers, foundations, etc. The quarries are located on the bank of the Con- 

 necticut river, stretching for two miles along its course. Channelers, steam 

 drills, and blasting are employed in the quarry. Average blocks are from two 

 to five feet thick, but blocks measuring 128 feet by 20 feet by 11 feet have 

 been loosened. The quarries are now 200 feet deep. 



The stone is of Triassic age, and has long been noted for the bird and 

 bird-like serpent tracks which occur in it. Chemical analysis shows it to 

 contain 70.11 per cent, silica, 13.49 per cent, alumina, and a small per cent, 

 each of iron oxide, manganese, lime, magnesia, soda, and potash. It has a 

 specific gravity of 2.35 and weighs 150.75 lbs. per cubic foot. It has a 

 crushing strength of 10,000 to 10,900 lbs. per square inch. 



The stone has been used to some extent for monuments but is primarily a 

 high-grade building stone, and as such has been shipped to all parts of the 

 United States. Its great durability is shown by the fact that on tombstones 

 which have been standing more than 200 years the lettering is still distinct. 

 The article is illustrated by thirty full-page plates, one a representation of the 

 brownstone in colors. T. C. H. 



The Lake Superior Sandstones. By H. G. Rothwell (Stone, Vol. IX., 

 No. 1, June, 1894, pp. 59-61). 

 The article is supplementary to an earlier one published in the proceedings 

 of the Michigan Engineering Society for 1891. The quarries at or near 



