Underfalls

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IMG_2981, originally uploaded by Mic2006.

There is a cool, wet breeze in front of the falls and I scrambled to the cascade’s edge over slippery rocks. It is possible to work your way beneath the water if you are careful. This odd picture was taken looking up from under the falls.

As Mark Harris points out waterfalls can either drop without touching the rock strata behind or they might cascade down in a frothy spray. Both of these scenarios are largely dependant upon the type of rock over which the water passes. If the top of the river rushes over a resistant strata and the base of the drop is of a more friable material the drop will probably be undercut. In this circumstance the water will fall free of the underlying rock face. This “plunge falls” is especially common in Southern Ontario where harder Silurian Age dolostones and limestones overlie softer Ordovician age shales.

If the rock strata is thinly bedded and the entire length of the fall’s drop is over a singular formation you will encounter a ramp effect. In this scenario the water never looses contact with the rock beneath.