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inferred from confining our observations to the exposure upon 

 Salem creek. The marl of Skulltown resembles closely that 

 which is seen in many other places as we approach the Delaware. 



The excavations at Woodstown are very extensive in con- 

 sequence of the excellent quality of the material and the circum- 

 stance that this is near the extreme southwestern termination of 

 the marl tract, or at least of that portion of it w^hich lies at a 

 sufficient elevation to be of easy access. The features of the 

 stratum where it is opened in the eastern bank of Salem creek, 

 are such as belong to a great number of other localities, more 

 particularly within the southern half of the marl region. 



The beds in the descending order are as follows : 



First, the usual covering of diluvium, in which there abounds 

 a considerable quantity of white quartzose gravel, and near to the 

 top of the subjacent marl a number of large rounded blocks of a 

 yellowish sandstone, scarcely calcareous. It is close grained, 

 and often excessively tough. It has been derived evidently from 

 a stratum once in place upon the upper surface of the marl, a 

 portion, I have no doubt, of the bed which still occupies that 

 position in many places not remote. I see every reason to con- 

 sider it as representing the stratum known as the siliceous lime- 

 stone of Mannington, Vincentown, and other points. It seems to 

 ditTer from this rock in the relative proportion of the sand and 

 lime, containing but very little of the latter. At the bridge over 

 Salem creek about a fourth of a mile to the west of the marl pits 

 where these rounded blocks occur, there exists in an undisturbed 

 condition a stratum of rock in the very position here assumed, 

 and of a composition and aspect strictly intermediate between 

 the almost pure limestone, and the above mentioned almost perfect 

 sandstone. It lies close to the water's edge, and has therefore 

 been little noticed. It effervesces pretty actively with an acid, 

 and has been found when burned in the small way to yield a lime 

 capable of slaking. It possesses a yellowish-gray hue, showing 

 the ordinary flinty sand which is its main ingredient, and in 

 addition, a trivial per centage of the green granules. 



The next deposit is the light-green marl, which does not overlie 

 the dark green in all parts of the bed, being absent in all the exca- 

 vations nearest the town. In the banks lower down the creek, as 

 at Mr. White's, the section exhibits a layer of the light green or 



