W. B. Clark— The Mataioan Formation. 437 



Raritan beds. The most important feature connected with 

 this occurrence is the presence of a typical Cretaceous marine 

 fauna,* part of the species being similar to the overlying Mata- 

 wan, and a flora* containing many representatives of genera 

 more recent than those in the Raritan below. Mr. E. W. 

 Berry ,f who has recently studied this flora, finds that only 37 

 per cent of the forms occur in the Raritan and among these the 

 oldest and most characteristic types are lacking. In an earlier 

 communication I referred to the lack of a clear line of separa- 

 tion between these beds and the typical Matawan above. At 

 the time of my first and only study of the occurrence, thirteen 

 years ago, the sections were much less distinctly exposed than 

 at present, slips obscuring the upper beds. I felt in much 

 doubt at the time as to whether the beds belonged to the Mata- 

 wan above or to the Raritan below, and although I at first 

 regarded them as Raritan and so mapped them, I finally 

 decided to refer them to the Matawan and changed my lines 

 accordingly before publication. On a recent visit to the locality 

 I found the line of contact clearly shown, and it is evident that 

 the Cliflwood clays represent an older horizon than the basal 

 Matawan elsewhere exposed. Messrs. Kiimmel and Knapp in 

 the recent Clay Report of the New Jersey Survey, have referred 

 these beds to the Raritan, but from their structural relations, 

 lithologic character, and contained fossils it is apparent that it 

 is equally impossible to refer them to that formation. All of 

 these features indicate that these deposits constitute a transi- 

 tional zone between the Raritan below and the Matawan above, 

 and that they should be given independent rank as a formation. 

 A study of the basal contact of the Matawan formation from 

 the Potomac to the Raritan rivers shows that the Matawan rests 

 on successively later deposits northward, thus indicating a grad- 

 ual transgression of the Matawan over the Potomac formations 

 southward. Near the Potomac river the Matawan overlies the 

 Patapsco formation, but farther north the Raritan soon appears. 

 In approaching the Severn river and on the Eastern Shore of 

 Maryland, deposits that suggest the Cliflwood beds occur be- 

 tween the typical Raritan and Matawan. In Delaware and also 

 in southern Xew Jersey similar deposits have been found by 

 the author and his associates, marine fossils occurring in the beds 

 at Bordentown. Characteristic concretions of iron carbonate, 

 frequently fossiliferous, have been found all the way from the 

 shores of the Chesapeake to Cliflwood on the Raritan, although 

 marine fossils have not been observed south of Bordentown. 

 These deposits are significant in furnishing the earliest known 

 Coastal Plain marine fauna, a fauna which apparently con- 

 tained the first strictly marine types of life to migrate into the 



*Hollick, A., The Cretaceous Clay Marl Exposure near Cliffwood, N. J., 

 Trans. N. Y. Acad. Sci., vol. xvi, pp. 124-136, pis. xi-xiv, 1897. 



fBull. N, Y. Bot. Garden, vol. iii, No. 9, pp. 45-103, pis. 43-57, 1903; 

 Amer. Geol., vol. xxxiv, pp. 253-260, pi. xv, 1904. 



