

62 The Upper Cretaceous Deposits of Maryland 



marked and pronounced stratified character, especially in some of the 

 clays which are finely laminated. A striking feature of these deposits is 

 the presence of amber which was described from beds of this age at " Cape 

 Sable" (North Ferry Point), Magothy River, by Troost in 1821. The 

 amber occurs in layers of lignitic sandy clay in the form of pellets. 



The light-colored white sands contain pinkish angular quartz grains, 

 and at times much nmscovite. A characteristic type of stratification is 

 seen in the sandy layers separated by thin laminae of dark-colored clay or 

 sandy clay which is often leaf-bearing. It was due to the frequency of this 

 laminated structure that Uhler was led to propose the name " Alternate 

 Clay Sands " for these beds. Such clay laminae, at Grove Point and other 

 localities have furnished an extensive flora. 



The Magothy deposits, particularly at "Cape Sable'' (Xorth Ferry 

 Point) on the Magothy River, afforded in earlier days not inconsiderable 

 outputs of alum and copperas, derived from the lignitic and pyritic beds. 

 The "Baltimore Alum and Copperas Works," at Locust Point, Balti- 

 more, produced large quantities of these products which Ducatel esti- 

 mated in 1834 as amounting to over $80,000 annually. 



The Magothy formation lacks the massive beds of highly colored clays 

 found in the Earitan, while the variable and rapidly alternating sands and 

 clays are infrequent in the latter. The materials of the Magothy are also 

 for the most part readily distinguished from the overlying Matawan by 

 the absence of glauconite in the former and by the lack of homogeneity 

 which is so marked a feature of the Matawan deposits. 



Strike, Dip and Thickness. — The strike of the Magothy formation is 

 essentially like that of the Earitan formation. Tt has a general northeast- 

 southwest direction throughout much of the area of outcrop, except in 

 Prince George's County where it is more nearly north and south. 



The dip of the beds is to the southeast and east and at the rate of about 

 30 feet to the mile, although this is somewhat increased in the case of the 

 outliers to the west of the main body of the outcrop. 



The Magothy formation has a maximum thickness at times of nearly 

 100 feet in the northern part of the district, but even here the thickness 

 is variable and in some places does not exceed one-half that amount. 



