Cochise College Student Papers in Geology

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Roger Weller, geology instructor

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Water Erosion
by Jarrod Swackhammer
Physical Geology
Spring 2007

Ramsey Canyon: Water Erosion

Southwest of Sierra Vista, Arizona, in the Huachuca Mountains there exists a unique canyon known as Ramsey Canyon. Famous for its bird-watching and rare Ramsey Canyon Leopard Frogs (Rana subaquavocalis), this canyon owes much of its shaping and unique physical features to water erosion. On this page you will be able to explore these different features in Ramsey Canyon made possible by the work of water.

When overlooking the upper part of Ramsey Canyon a “V-shape” is evident (see picture above). This is representative of a V-shaped valley which indicates its shape has been carved out by the work of a river, or in the case of Ramsey Canyon, the work of Ramsey Creek. Ramsey Creek flows at the vertex of the “V” slowly carving the canyon further.

On its way to lower elevations, Ramsey Creek erodes all kinds of rocks. With the steep stream gradient of the canyon, Ramsey Creek can erode limestone effectively in a vertical fashion. The following picture is exemplary of this action and is an area of Ramsey Canyon known as “The Box”.

The limestone here has been carved and eroded dramatically by water, but water erosion is more effective in some places here than in others. Due to the different resiliencies to erosion by different rocks, knickpoints can be formed where more resilient rocks exist above less resilient ones such as this limestone. In these knickpoints water erodes the weaker rock faster making the topography between the different rocks more extreme and therein creating waterfalls. The following picture shows such a waterfall upstream of the highly eroded “Box”.

In this region of Ramsey Canyon, the creek exists as a perennial stream, though the same cannot be said about it in lower elevations, as it does not flow year round there. Despite the consistency of its flow in the deeper canyon areas the erosion brought about by Ramsey Creek varies in its rate by season. In periods with little rainfall or snow melt the creek can only be found holding water in its higher elevations and very intermittently in lower elevations. The trickle of water on the rocks in this period of time has a relatively small effect on the erosion of the canyon. However, Ramsey Creek can change dramatically from a trickle to a torrent in the wake of the summer Southern Arizona rains. The streams capacity and velocity can change drastically after heavy rainfall, increasing the rates of erosion. The greater stream capacity allows Ramsey Creek to move heavier and larger quantities of rocks eroding off their edges on one another until the rocks, banks, and streambed are worn smooth. Eventually, these rocks are dropped to the streambed where the streams capacity waivers.

Some pictures of Ramsey Creek a few days after heavy rainfall:

During flooding and directly after heavy rainfall “The Box” are of Ramsey Canyon is dangerous and impassable. Also the sides of the canyon are not easy to climb up! This has been a look at Ramsey Canyon water erosion, making the canyon the beautiful feature it is today.

All photos copyright: Jarrod Swackhamer (do not use without permission from photographer)

http://en.wikipedia.org/wiki/Erosion

http://en.wikipedia.org/wiki/Weathering#Hydraulic_action

http://www.nature.org/wherewework/northamerica/states/arizona/preserves/art1973.html

http://www.greglasley.net/ramseycanfrog.html