358 E. B. MATHEWS AND W. J. MILLER — COCKEYSVILLE MARBLE 



in this region are found in small outcrops, where they strike parallel 

 with the axis of the valley and dip northward at a decreasing angle as 

 one passes from the south and west to the limits of the overlying Wissa- 

 hickon formation. The dip is, however, generally steeper than 45 degrees. 

 As the limestone circles round the southwestern anticline the strikes 

 change in conformity with the contour of the major fold, and the dip is 

 uniformly away from the quartzite and beneath the Wissahickon schist 

 lying to the west of Lake Roland. Between the eastern and western ends 

 of the anticline the limestone is compressed within minor folds in the 

 quartzite at Mount Wilson and in several places along Moores branch. 

 It is lacking, however, in its normal position (between the quartzite and 

 the Wissahickon) from a point 1 mile east of Cockeysville to the western 

 limit of the fold, with the exception of the single exposure, already re- 

 ferred to, occurring at Mount Wilson. In the valley above Lake Roland 

 the limestone is only exposed once or twice, as at the junction of Jones 

 falls and Roland run. Such structural observations as can be made are 

 in accord with the synclinal structure of this small southern offshoot of 

 the Greenspring valley. The limits of the limestone south of the Green- 

 spring valley are determined on the east by a north and south fault 

 passing from Sherwood through Ruxton to Lake Roland and thence into 

 the lowland above Mount Washington. The exposures of marble from 

 Sherwood to Glenarm show relatively simple monoclinal dips to the 

 northward, except in the region southwest of the Wissahickon, where 

 this marble unites with that of the Dulany valley, and in the vicinity of 

 Glenarm, where the limestones fold sharply around the upturned anti- 

 cline of quartzite already described. At each of these points there is 

 minor folding, and the local structure is much confused in its detail, 

 although harmonizing well with the broader structure as here outlined. 

 The exposures for the most part are poor and occur almost exclusively 

 in small private openings, where the stone has been extracted for lime. 



Dulany valley. — This valley, which extends for 5 miles northeasterly 

 of Lutherville, with an average width of from 1 to 2 miles, shows numer- 

 ous exposures west of the Gunpowder river, but is almost entirely lack- 

 ing in the same from the Gunpowder to its easternmost limit. Enough 

 observations, however, have been made to show that the limestone is 

 here very flat, with several minor crests and folds extending parallel to 

 the longer diameter of the valley, the limestone dipping beneath the 

 Wissahickon on the north at a varying angle. 



North of Merediths bridge, where the Jarrettsville turnpike rises from 

 the limestone valley to the level of the plateau, the strike of the lime- 

 stone changes rapidly through west and northwest to a little east of north, 

 following the course of the Gunpowder river. From the vicinity of 



