Asian Influences

This koi, a domesticated variety of the common carp Cyprinus carpio was photographic in the section of the creek between the Covered Bridge and the Rex Avenue Bridge. Consulting an online guide to koi fish, this appears to be of the Kararimono variety, which upon further investigation appears to be the generic name for koi that do not quite match more carefully specified types. From colored carp originally bred in China, koi can trace their lineage to Japan of the 1820s, and somehow found their way into Wissahickon Creek.

This Chinese Goose was photographed downstream from the Rex Avenue Bridge. The name "chinese goose" is an official designation of American Poultry Association's Standard of Perfection. Bred from the Swan Goose Asner cygnoides, it is of Chinese origins and can easily be identified by the strong basal knob on the upper side of the bill.

A less benign residents of the park is a copse of Trees of Heaven Ailanthus altissima located between the Pro Bono Publico Fountain and the Valley Green Parking lot. An invasive tree brought here in the 1740s a period of chinoiserie excess from China where it enjoyed a medicinal reputation for curing mental illness and baldness, its ability to thrive in harsh environments became the central metaphor for the book A Tree Grows in Brooklyn.

An attempt to eradicate the tree in the past only seems to have inspired vigorous new growth. Its flower, notably malodorous, can be seen in bloom, whence the scent may soon be experienced by the casual stroller, who can determine whether the name "stink tree" is applicable.

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Ice Age

The blue shows the scope of the most recent Ice Age, the Wisconsinan (17,000 - 22,000 yrs.).

The green shows the edge of the Late Illinoian (132,000 - 198,000 yrs.) ice cap.

The orange shows the edge of the of the Pre-Illinoian (>770,00 yrs) ice cap.

The yellow shows the stratified drift, the outflow resulting form the melting of the last two Ice Ages.

The position of the ice cap can be determined by the till—the debris resulting from the grinding of the surface rock as the massive ice shelf moved over the it. From the maps, it is clear that the most recent Ice Ages never reached the Wissahickon Gorge.

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