Bridge;ton Formation — Summary. 13 



Marlton, at Irish Hill north of Chews Landing, at Adams Hill 

 south of Mickleton, at Point Airy east of Woodtown, and at 

 Big Mannington Hill southwest of the same place. Hough- 

 ton's Hill and Irish Hill show well the distinctive characteristics. 



In more detail, the material of the formation is primarily 

 quartzose. The bowlders and larger cobbles are mostly of quart- 

 zite or sandstone, and the smaller cobbles and pebbles are mostly 

 }f quartz and chert; but bits and even large masses of crystal- 

 ■ne rock, such as granite, gneiss, schist, diabase, etc., are present 

 m most places, though not generally abundant. Some of the 

 pieces of crystalline rock appear to have come from the meta- 

 morphic formations along the Delaware below Trenton; but 

 the granitic and diabasic fragments come from other and more 

 northerly sources. Some of them are like rock in the High- 

 lands, from which they probably came, and some are like the 

 igneous rocks of the Newark series. Many of the quartzite and 

 quartzose sandstone bowlders and cobbles are so like the Paleo- 

 zoic sandstone and quartzite of northern New Jersey as to be 

 indistinguishable from them. Pieces of Highfalls (so-called 

 Medina and Oneida and Shawangunk) sandstone are definitely 

 recognizable ; so, also, are bowlders of quartzite derived from 

 the Miocene sandstone which once overspread the Coastal Plain, 

 and which was cemented locally into quartzite, though in most 

 places not cemented at all. The Miocene bowlders are abundant 

 locally, and are known as "bulls heads." Many of them have 

 a pinkish or purplish tone. 



Besides the sandstone fragments of quartzitic type, there are 

 large and small fragments of red shale and red sandstone which 

 came from the Newark series to the north, oir from some other 

 formation so similar to it as not to be readily distinguished. 

 There are occasional pieces of black shale, similar to the Locka- 

 tong shale of the Newark series, and pieces of grayish arkose 

 sandstone which are referred with confidence to the Stockton 

 formation of the same series. The crystalline rock and the red 

 shale and sandstone go together in the sense that where one is 

 found the others are likely to be. They are more common at the 

 base of the formation than in any other part of it, and are most 



