CLAYS. 239 



produce a small quantity of pressed brick. The clay used is a more or 

 less mottled, gritty, yellow or reddish clay, which is covered by a thin 

 layer of sandy soil and commonly underlain by a bed of sand. At only one 

 point, namely, the yard of Green and Harrison, is the underlying crystalline 

 rock encountered. The clays in general are very tough and plastic, some- 

 times quite sandy, and they contain a variable quantity of stony material 

 which ranges in size from small pebbles up to large boulders, most of these 

 being of crystalline character. This stony material is not found to be 

 uniformly distributed through all the beds, but seems to run rather in 

 streaks, the greatest quantity of it having been observed in the bank of 

 W. J. Eeady, and Green and Harrison. 



At G. E. Bedford's yard, the clay shows an average thickness of 13 feet 

 with a maximum of 17 feet, and is underlain by a hard bed of sand and 

 gravel. It is a mottled gritty clay with scattered mica fragments and many 

 limonite stains running through it; and it contains also many decomposed 

 pebbles of crystalline rock. The clay pit is a large shallow excavation lying 

 to the south of the yard and the working face has a height of from 6 to 8 

 feet. The material is red-burning, and for the manufacture of bricks the 

 run of the bank is commonly used. This is necessary because the clay seems 

 to vary somewhat in its physical character. Thus, for instance, it is not 

 safe to use that found in the north end of the pit alone, because it is very 

 tough and cannot be used without cracking. It is mixed therefore with the 

 more sandy portions of the bed. 



Adjoining the yard of Bedford on the west is that of W. B. Davis. This 

 pit, which is a large shallow excavation, lies to the south of the yard, and 

 has a working face of from 6 to 7 feet in height. The clay is similar to that 

 in Bedford's bank, but seems to contain fewer stones. 



Adjoining Davis' yard on the east is that of W. J. Eeady. The clay pit 

 which lies to the northwest of the yard is much deeper than the neighboring 

 excavations and also lies at a slightly lower level, for the upper surface of 

 the clay is uneven and slopes towards the river. The clay in general is 

 somewhat similar to that found at the two preceding yards but contains 

 more stones and boulders than are found in either Bedford's or Davis' 

 bank. The thickness of the clay is said to be at least 18 feet, and it is 

 probably underlain by sand. Here in a working face of perhaps 200 feet 

 in length they recognize three different kinds of clay, only one of which 

 they claim can be used alone. If either of the other two is used by itself, 

 it results in an imperfect product. The physical and chemical characters 

 of these three clays are given in the table opposite page 235. 



