GEOtOGY OF DELAWARE COUiNTY. 



It cannot be supposed that in a district of country so very limited in its ex- 

 tent as the County of Delaware, there will be found in the details of its Geology 

 many facts to interest the general reader. Still there are a few, that when 

 brought to the notice of an inquiring mind, cannot fail to attract attention and 

 lead to furtlicr investigations, alike pleasing and useful. 



As preliminary to the consideration of the Geology proper of the County of 

 Delaware, a topographical view of the territory embraced within its limits will 

 be presented. 



The drainage of the County is principally eflfeeted by five large creeks and 

 their tributaries, that traverse it in their course to the Delaware River, viz : 

 Cobb's, Darby, Crum, Ridley, and Chester Creeks ; by the Brandywine, that forms 

 a part of our western boundary, and by Naaman's Creek that empties into the 

 Delaware a short distance bel'ow the junction of the circular line with that river. 

 A small part of Radnor township is drained by the Gulf Creek, and a still smaller 

 part of the same township by Mill Creek, both of which discharge their waters 

 into the Schuylkill. 



Of these creeks the Brandywine is much the largest. The next in size is 

 Chester Creek, which enters the County by two principal branches, designated 

 " East " and " West." These branches are both good mill streams. They unite 

 their waters at Crozerville, and the main creek empties into the Delaware at 

 Chester. Darby Creek, the next in point of size, also has its origin in two prin- 

 cipal branches, known as " Big " and •' Little " Darby Creoks. These unite at 

 the tlour mill of Tryon Lewis in Radnor. Ithan Creek, another principal branch, 

 also unites with it in the northwestern part of Haverford township. The main 

 stream, thus formed, after passing Darby, the head of tide, unites its waters with 

 those of Cobb"s Creek, forming a large tide water stream, even larger than 

 Chester Creek. Crum and Kidlei/ Creeks are each of them considerable streams 

 before they cross the dividing line of Chester and Delaware Counties. They 

 pursue the same general course, and only distant from each other from one to 

 two and a-half miles. A little above tide water, these creeks approach within 

 a half mile of each other, but again diverge and enter the Delaware between the 

 borough of Chester and Tinicum Island. Cobb's Creek rises about the dividing 

 line of Radnor and Haverford, traverses the latter township, and afterwards 

 forms the boundary line between Delaware County and the consolidated city of 

 Philadelphia, to its junction with Darby Creek. 



Besides the streams enumerated, the County has other mill streams of less 

 note, as Hook Creek, which empties into the Delaware above Marcus Hook ; 

 Little Cnim Creek which unites with Crum Creek, a short distance before that 

 stream reaches the river; Alucanippates, a branch of Darby Creek; Xat/lor's Bun, 

 a branch of Cobb's Creek; Concord Creek And Green's Creek, branches of the west 

 branch of Chester Creek ; Rock;/ Run, a branch of the east branch of the same 

 stream, and Beaver Creek and I{arve;/'s Run, branches of the Brandywine. The 

 Gulf Creek turns one mill in Delaware County ; and besides those enumerated, 

 there are several streams of sufficient size for light mill powers. 



The surface of the County is decidedly undulating, and in some parts hilly 

 As the direction of the streams indicate, there is a general slope in the land 



