review of prp:vious investigations. 323 



upon the western shore of Maryland, Darton having described a consid- 

 erable portion of the upper Cretaceous of this area under the name of 

 the Severn formation, while the observations of Mr Hollick have chiefly 

 embraced the deposits in northern New Jersey beneath those now under 

 consideration, although the basal members of the upper Cretaceous in 

 this area, as well as the transported fragments of the same formations 

 upon Staten island and Long island, have been discussed. 



During recent years Mr Lewis Wbolman,* of Philadelphia, has col- 

 lected a large amount of valuable information regarding the well-borings 

 throughout the northern Atlantic Coastal plain. This data is of much 

 value to the field geologist in helping him to control his conclusions. 

 Mr Woolman's records have been frequently consulted, although the 

 authors have often differed from him in the interpretation of the data. 



The later history of investigation of the Upper Cretaceous formations 

 in this district is confined largely to the work carried on under the direc- 

 tion of the senior author by the instructors and students of the Johns 

 Hopkins University. Several papers t have already appeared and others 

 are in course of preparation, in which more detailed discussions will be 

 found regarding both the geological and paleontological aspects of the 

 subject. 



Topographic Features. 



The Upper Cretaceous formations constitute a part of the great area of 

 lowland bordering the Atlantic coast of North America and known as 

 the Coastal plain. This plain extends with constantly narrowing limits 

 from the southern Atlantic states across the area now under consideration, 

 beyond which its continuity becomes broken, although represented in 

 the southern portions of New England and in the various islands along 

 the coast. The width of the northern Coastal plain varies from some- 

 what over 100 miles in central Maryland to scarcely 25 miles in eastern 

 New Jersey. 



The Upper Cretaceous formations occupy a belt within the Coastal 

 plain which extends from northeast to southwest and which is separated 

 b}' a tract some 10 or 15 miles in width, composed of Lower Cretaceous 

 deposits, from the Piedmont plateau. This belt of Upper Cretaceous 

 strata varies in width from about 25 miles in' eastern New Jersey to barely 

 a mile in southern Maryland. Its more unyielding deposits have pro- 

 duced a ridge of high land, which, with varying elevations, extends along 



♦Annual reports of the state geologist of New Jersey, 1889 to 1895. 



t Rept. State Geologist N. J., 1892, pp. 167-245 ; ditto, 1893, 1894, pp. 329-355 ; Jour. Geol., vol. ii, 

 1894, pp. 161-177 ; Bull. Geol. Soc. Amer., vol. 6, 1895, pp. 479-482 ; Johns Hopkins Univ. Circulars, 

 vol. 8, 1889, pp. 20, 21 ; ibid., vol. 15, 1895, pp. 3, 10-12, 14, 15, 17. 



XL,IX— Bull. Geol. Soc. Am., Vol. 8, 1896 



