99 
The limestone region is about eight miles wide and lies south 
of the slate belt. It is in reality a great plain with many inter- 
secting, gentlv sloping valleys. I quote from the Second Geo- 
logical Survey of Pennsylvania where it is stated that its “north 
border commences about half a mile north of Siegfried's Bridge 
and continues nearly due east until it reaches a point a little south- 
west of Bath. Here it makes a northward bend of about a mile 
and, passing through Bath, it continues with a zig-zag border 
almost due east to Nazareth. At the latter point it bends toward 
the northeast and continues in this direction through the village of 
Martin's Creek and then extends as a strip about half a mile 
wide parallel to the Delaware river as far as Belvidere." Here 
it leaves Pennsylvania and crosses into New Jersey. The 
southern border of the limestone belt is where it meets the South 
mountains with this exception, that at Bethlehem it continues 
through a break in the mountains and forms the Saucon valley 
basin. This limestone plain has an elevation of about 400 feet, 
with the hilltops approximating 450 feet. It consists largely of 
rich farm lands underlaid by limestone soil and maintaining some 
few patches of woodland. 
The South mountains or Durham and Reading hills form the 
southern, syenite, belt. This region lies south of the Lehigh 
river, extending about five miles within the county limits. It is, 
however, actually seven miles wide if the portion which lies in 
Bucks county is included. The South mountains consist of 
parallel highland ridges which are a continuation of the Highlands 
of New York and New Jersey through eastern Pennsylvania 
ending in the Schuylkill river in Berks county. Locally, they 
are also known as the Lehigh mountains. They are long and 
narrow ridges with gentle slopes and rounded summits with a 
maximum altitude of 1,100 feet. Between these ridges lie valleys 
of rich limestone land but the soil on the mountains is rocky and 
poor. The mountain slopes were at one time heavily wooded but 
none of the original forest remains. Second growth timber has 
covered portions of the hills but this is occasionally denuded in 
patches by mountain fires. The rock formation of these ridges 
has been referred to the Laurentian age. Large rounded bowlders 
