88 Notice of a Geological Model. 
those levels along the crests of the ridges, when not broken by 
transverse fissures. The Blue or Kittatinny Mountain, the south- 
ernmost of these nearly parallel ranges, is probably the highest. 
The coal range is next in elevation, and there is some lofty 
ground, forming Short Mountain, between Peter’s and Berry’s 
mountains. ¥ 
Geological F'eatures.—Under this head we shall here be very 
brief; because that subject is not the primary object of this ad- 
dress ; and because the region has received or will receive, ample 
investigation by the state geological survey, with all the combined 
advantages resulting from the official resources, the science and 
the experience of its able conductor. The results of that great 
work it would be premature to anticipate. The positions of the 
various formations and of the respective members of the groups 
of strata, within these limits, have already been indicated in the 
annual reports of Professor Rogers. 
In contemplating this region, it appears to us that its most inter- 
esting features are attributable to the undulating and broken or 
upheaved character of the formations, by which process some of 
them are repeatedly brought to the surface, in long elevated 
ridges, and again dip at high angles and form basins which en- 
close or support the superior strata—the carboniferous series being 
of course the highest. These circumstances confer a remarkably 
picturesque character upon the scenery, particularly where these 
parallel ridges are intersected by the Susquehanna, the Juniata, 
and the Swatara rivers. No part of Pennsylvania is so rich in 
pictorial beauty as the borders of the noble Susquehanna, or has 
furnished so many subjects for the skill of the painter. 
The spectacle here presented, by this river, cutting across in 
its singular passage, nearly at right angles, through so many ridg- 
es of extremely hard rocks, would of itself furnish a theme for 
geological speculation. Phenomena like these are well illustrated 
by the mode of representation we have adopted. The numerous 
cross fractures marked by the frequent gaps through the moun- 
tains and by the remarkable ramifications of the Swatara, in the 
Pinegrove coal region, could by no other process of exhibition 
be rendered so intelligible. 
The Coal Formation.—It forms no part of the plan of the wri- 
ter to encumber this communication with minute details. With 
regard to the southern branch, more especially, it is the less neces- 
