CLAYS OF BURLINGTON COUNTY. 385 



brick-clay pits at Bordentown, but only 2 feet is exposed above 

 the talus, and there is 10 to' 12 feet of sandy loam overburden. 

 It is fairly accessible for shipping by water. 



The clay (Lab. No. 614) differs from the Bordentown ma- 

 terial in having- a lower air and fire shrinkage, and does not burn 

 to steel-hardness at so low a temperature, nor to so deep a red. It 

 mixes up with 27.1 per cent, water, and has an air shrinkage of 

 7 per cent. Its average strength is 145 pounds per square inch. 

 At cone 05 the fire shrinkage is 0.3 per cent., absorption 15.05 per 

 cent., color light mottled-red, and not steel-hard. At cone 01, 

 fire shrinkage 2.3 per cent., absorption 11.76 per cent., color red 

 and bricklet steel-hard, so- that the material could be burned to a 

 good brick at a low cone. 



Rancocas. — Clay Marl II is exposed at an abandoned brickyard 

 (Loc. 125) on the northeast side of Rancocas creek, three-fourths 

 of a mile due north of Borton's Landing and west of Rancocas. 

 It shows well how an otherwise good deposit of clay may be 

 ruined by the formation in it of a perfect network of iron oxide 

 crusts. These are sometimes found in Clay Marl II, and their 

 presence should have been determined beforehand by careful bor- 

 ing or a few test pits. An expensive plant was erected and 

 abandoned. 



Mo or est own. — An exposure of Clay Marl II is found at the 

 crossroads 1 mile northwest of Moorestown and on the road to 

 North Pennsville (Loc. 128). The clay outcrops in the ditches 

 along the road for some distance, and a boring made to a depth 

 of 6 feet 4 inches did not pass through it. The upper layers of the 

 section were chiefly a chocolate color, and passed downward into 

 a mixture of yellow and chocolate clay and finally into' bluish- 

 black material. Although the clay contains much mica, there is 

 no evidence of pyrite. The deposit was also' quite dry, until the 

 lower foot of the section was reached. There is very little over- 

 burden, and the slope of the land would insure good drainage. 

 Careful search should be made to prove the absence of limonite 

 crusts, as there seemed to be a slight tendency towards their for- 

 mation where the boring was made. 



In the laboratory examination the clay (Lab. No. 610) was 

 found to be rather free from grit. It worked up with 35 per cent. 

 25 aG 



