60 The Lower Cretaceous Deposits op Maryland 



shades of red, yellow, brown, maroon, and lavender, in piebald tints and 

 patterns of great beauty. The purple coloring is very characteristic. 

 Extensive lenses of these brilliantly colored clays occur in the eastern 

 part of the city of Baltimore, where they constitute an important re- 

 source for the brick industry. They were penetrated to a depth of 40 

 feet in the excavations for the new outfall sewer for Baltimore City 

 without reaching their base, and were so resistant as to require the 

 almost constant use of the mattox. At Bayview these same clays were so 

 resistant as to require blasting. The clays are at times drab or black in 

 color, from the admixture of carbonaceous matter. Yery definite beds 

 of lignite occur at some points, notably near Jessups and at Clifton 

 Park, at both of which points the lignite has been employed to some 

 extent as a fuel, although the beds are rarely more than a foot in 

 thickness and are of small horizontal extent. Lignitized twigs, limbs, 

 and trunks always strongly compressed as well as fossil leaves are not 

 uncommon in these deposits. Lignitized stumps have occasionally been 

 found in erect positions. The comminuted carbonaceous matter is at 

 times so abundant in the clays as to produce an earthy lignite of dead- 

 black color. A deposit of this character filled with lignitized stems 

 occurs in the valley of Broad Creek, Cecil County overlying the basal 

 conglomerate before mentioned. Occasionally the drab or lignitized 

 clays carry carbonate of iron as at Gaither's Dam in Stony Run, Anne 

 Arundel County, but the deposits are of small economic importance. 



Deposits of red and yellow hydrous oxide of iron are at times found 

 in sufficient extent to possess economic value as pigments. Such deposits 

 frequently occur at the top of sand beds which are overlaid by drab 

 clays, as at the base of the terra cotta clays at Federal Hill. 



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

 in Maryland is in a general northeast-southwest direction, becoming 

 more nearly north and south as the valley of the Potomac is reached, to 

 the south of which, in Virginia, the strike is north and south. 



The dip of the beds is to the southeast but is variable in amount, espe- 

 cially in proximity to the Fall-line, where in places it largely exceeds the 

 dip of the main body of the deposits farther eastward. The dip to the 



