628 



STOSE AND LEWIS — TEIASSIC IGNEOUS ROCKS 



forms the northern limit of the intrusive mass and connects with the 

 north end of the Gettysburg sill. 



The main intrusive body is thus seen to have the general form of a 

 great trough that comes to the surface on the east as a great sill between 

 the sedimentary strata and on the west as a sill along the flat overlap 



SOUTH MT(\ 



PIGEON HILLS 



Section D~D' 



TRIASSIC IGNEOUS ROCKS T RIASSIC SEDIMENTS PALEOZOIC LIM ESTONES CAMBRIAN SANDSTONES 



(intrusive diabase) AND SHALES AND OLDER ROCKS 



(including slates of u nl<nownage) 



Figure 2.~Sections across the Triassic Rocks of the Gettysburg Area 

 The sections are along the lines marked on figure 1, and show the structural relations 

 of the formations and the vent up which the igneous rock is supposed to have come into 

 the basin. The vertical scale is somewhat exaggerated. 



basal contact, and terminates at the ends in large cross-cutting bodies 

 (see figure 2). That the trough is not complete throughout the area, 

 however, is shown by the absence of the sill at the basal contact in the 

 immediate vicinity of York Springs, where the Paleozoic limestone floor is 

 overlain by Triassic sediments. 



The Chestnut Hill igneous mass is a diabase sheet at a higher horizon, 



