Page:Historic towns of the middle states (IA historictownsofm02powe).pdf/340

 Philadelphia stands, and necessarily stands on the straight, ruler-like "Falls line" which passes through every city site from New York to Montgomery, because this prodigious slip changes river navigation wherever it crosses a river valley. Where marine navigation stopped to-day and then, Penn put his city, its site a peninsula about which two rivers joined, a rich alluvial plain, covered with glacial clay, with schistose rocks cropping out across it, the palæozoic marble of the Atlantic coast hard by, and a strip of green serpentine crossing the country from the highest points in the future limits of the city to Chester County, its first granary and feeding ground. These things—the half-sunken Lower Delaware River spreading into Delaware Bay, the term of navigation at the junction of two rivers, and the abrupt approach to the sea of a formation elsewhere miles from the ocean—make Philadelphia all it is in outer look, a flat city built of its own clay, garnished with its own marble, a seaport knowing the sea only in its rivers.

In this inland port, as you float in either river, seafaring masts and main rigging, black and tarred, silhouette against the tender green of growing fields. The early houses were