24 CRETACEOUS PALEONTOLOGY. 



the State. .This. fauna! element is of such a nature as to make it 

 reasonable to conclude that the position of its introduction in 

 successive sections across the State marks a contemporaneous 

 horizon. The first appearance of this faunal element at Atlantic 

 Highlands is at the base of Clark's Mount Laurel sand at that 

 locality. Here there is a slight lithologic difference between the 

 coarse marly sand carrying this faunal element and the finer 

 micaceous sand beneath, so that there is here some lithologic 

 reason for dividing Knapp's Wenonah to accord with the paleon- 

 tology. At Mullica Hill, in Gloucester County, this faunal ele- 

 ment has been found at least 20 feet below the base of the marl 

 bed there shown, and it may occur still lower. With this con- 

 temporaneous faunal horizon as a datum, line, it is seen that 

 neither the basal boundary of the Mount Laurel nor the upper 

 boundary of the Wenonah, as the beds were originally described, 

 represent contemporaneous horizons across the State. The 

 summit of this sand-filled interval becomes later and later in time 

 in passing from the north to the south because of the longer 

 duration in that direction of the sand-depositing; conditions. By 

 limiting the name Mount Laurel to the upper sands containing 

 the new faunal element, as was done by Clark himself at Atlantic 

 Highlands, and the Wenonah to the beds below, which on the 

 whole are finer and quite micaceous, it may be possible to give 

 both these names a place among the Cretaceous formations of 

 New Jersey. If the lithologic distinction between the two hori- 

 zons was as clear all the way across the State as it is at Atlantic 

 Highlands, this could easily be done and the two formations 

 separately mapped. To the south, however, the lithologic differ- 

 ences become much less distinct, although for much of the dis- 

 tance across the State the lower division of the sand, the We- 

 nonah (using the term in the restricted sense) is slightly finer 

 and more micaceous and clayey, while the upper (the Mount 

 Laurel) is more ferruginous and glauconitic. 



Still another point in the stratigraphy of the New Jersey Cre- 

 taceous has been given different interpretations by different 

 workers in the field. This is the "yellow sand" near the summit 

 of the section. This formation was given a definite place in the 

 section by Cook between the "yellow limestone" and "limesand" 



