248 Organic Remains of the Ferruginous 



ly relative position. -Clays containing lignite occur in the midst of 

 arenaceous deposits, — above tliem, — and below them : similar clays 

 OCjCur under similar circumstances in Europe without being there re- 

 ferred to the plastic clay formation. If tlie latter does exist in con- 

 tact widi our marls, it will be found, as I formerly mentioned, at 

 Bordentown, White Hill, and some other places in New Jersey. 

 Prof. Eaton informs me that he has uniformly observed the clay and 

 lignite beds to be subordinate to the marl : I have noticed tlie same 

 fact in some places and the reverse of it in otliers ; and must repeat, 

 that in this respect there appears to be no uniformity. 



The strata at tlie Chesapeake and Delaware canal present a very 

 interesting series of phenomena; and as the excavations at this place 

 have been carried to a considerable depth, and an accurate register 

 kept of their mineralogical and geological features, I will here offer 

 a vertical section of the strata taken about a quarter of a mile west 

 jof the summit level by Air. A. A. Dexter, one of the Engineers. 

 At this place the excavation is upwards of sixty four feet deep ; and 

 beginning at the surface, the following appearances are observed. 



1. Several beds of red sand, gravel and iron crusts, containing 

 occasional large fragments of primirive rocks. Diluvial. 



2. Daik blue mica sand, without organic remains. 



3- Clay and sand of a bluish brown color, containing multilocu- 

 lar shells. Echini, Amber, pyrites, and Lignite : the latter being even 

 imbedded in the solid casts of the ammonites. 



4. Dark green and blue argillaceous sand, containbg tlie same 

 products. 



5. Dark grey sand and clay ; atliin stratum with few fossils. 

 €. Loose green micaceous sand with Lignite and Amber. 



7. A darker colored argillaceous sand, with similar products. 



8. A light gray loose sand, with Lignite, Amber, and Pyrites. 



A litde farther west all these strata are penetrated through in tlie 

 progress of excavation, and are found to rest upon yellow ferrugin- 

 ous sand and gravel, containing considerable masses of these sub- 

 stances cemented by oxide of iron; but no traces of Lignite, Am- 

 ber or organic remains have been observed, although this stratum has 

 been penetrated to a very considerable depth. 



It will be seen, then, that lignite occurs in the first bed which con- 

 tains organic relics ; that it Increases In quantity as we descend, until 

 the mass of strata reposes on a bed of sand, which in physical char- 

 acters most resembles the upper, or diluvial deposits of this section- 



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