269 



micaceous, yet contains a very sensible proportion of the green 

 particles. No fossils appear in it. It has a strong sulphurous 

 odour, and presents the yellow efflorescence and astringent taste 

 of copperas, and resembles pretty closely that at Johnson's, near 

 Mount's mills. 



This material manifestly underlies the true greensand, which 

 here and at Bordentown, and indeed generally throughout the 

 belt of country bordering the Delaware, has been extensively 

 swept away along the northwestern margin of the formation by 

 denuding currents. 



At CostiU's mill the marl is pretty much of the same character, 

 containing perhaps rather more of the black clay and siliceous 

 sand. Sulphuret of iron also occurs in it, in little nodular lumps. 

 It smells strongly of sulphur. When applied in light dressings to 

 the land, it has been found useful. It is said to contain shells and 

 shark's teeth. 



On the Rancocus, near Franklin Park, the good marl lies at 

 the level of the tide, being covered by the yellow ferruginous 

 sand, and has much clay mixed with it. It has been found very 

 beneficial,^, but is regarded as inferior to that which lies higher up 

 the Rancocus. It contains fossils. 



Higher up the Rancocus, the marl extends to Pemberton and 

 Vincentown, and, it would appear, almost to the vicinity of the 

 Pine Cottage. 



Marl from Pemberton Mills. — Upper part of the Stratum. 



Description. — Colour, yellowish pea-green ; the washed grains 

 of a darker green and of small size. 

 Composition. — In 100 parts: 



• Greensand, ... 54-13 

 Clay, - - - - 20-47 

 Quartzose sand, - - 25.40 



10000 



The proportion of potash in this marl, by direct analysis, is 

 6'5 per cent. 



23* 



