382 



THE NATIONAL GEOGRAPHIC MAGAZINE 



WISSAHICKON CREEK AT VAPPEY GREEN 



Photograph by William H. Rau 

 EAIRMOUNT PARK, PHILADELPHIA 



With its more than 3,000 acres, Fairmount is one of the largest city parks in the world 

 and is Philadelphia's special pride. It extends along both banks of the Schuylkill River for 

 a distance of four miles. Skirting the picturesque Wissahickon Creek, which flows into the 

 Schuylkill, is the famous Wissahickon Drive. 



of rocks, some strata pure limestone and 

 others clayey or argillaceous limestone. 



These two kinds of rock are mixed in 

 proper proportions and ground to impal- 

 pable powder. Huge crushing machines 



munch hungrily their diet of stone, day 

 in and day out, passing their grist on 

 down to giant grinders having maws filled 

 with steel flails that fly around at high 

 speed, propelled by a central shaft; and 



