Cave Rimstone Mimics Adobe Walls
It’s nice to know that nature has a sense of humor. We copy it all the time, and sometimes it copies us. One example is within Gardner Cave in northeastern Washington. This cave system contains an abundance of rimstone pools (gours), which mimic American Southwest adobe masonry walls.
Pictured to the left, gours form through constant, never-ending dripping of dissolved calcium deposits. These incessant drips of calcium-rich water eventually drill holes into sloping cave floors. The water crystallizes forming the walls where the gradient is steep. These walls act as dams for the dripping water (Sparrow et al. 2010).
The same process that formed the rimstone walls developed Gardner Cave itself in a millions-of-years process. Approximately 500 million years ago, ocean covered northeastern Washington, and, of course, sea creatures died as they do. Their calcium- and dolomite-rich bodies littered the surface, contributing to beds within the Metaline Limestone Formation (Campbell 1947; Sparrow et al. 2010). Starting 205 million years ago, the Kootenay Arc docked on northeast Washington (Sparrow et al. 2010 [via Alt and Hyndman 1995:67]). The docking aided folding and uplift of the area, setting the stage for the cave’s shape. Throughout the Pleistocene (2 million to 10 thousand years ago [Chronic 1983:xii]), glaciers covered the area, then receded. The resulting abundance of water soaked through the soil and into the limestone, dissolving it. Currently, the cave spans 1,055 feet (Sparrow et al. 2010). The process continues today.
A guide will show you the process during a cave tour. The tours are the only way to visit the caves, which is a wonderful way, quite frankly. A short path leads to them. The trail extends northward to Canada. The footpath once linked Washington with British Columbia, but felled trees and large debris now obstruct the border. However, crossings do exist along Highway 2, which provides access the park, so Canadians can easily visit the caves as well. To learn more, visit http://www.stateparks.com/crawford_pend_oreille.html. The park opens on May 22, and remains so through September 1.
Cave Rimstone Mimics Adobe Walls by Shari Maria Silverman is licensed under a Creative Commons Attribution 3.0 Unported License.
Alt, David and Donald Hyndman
1995 Northwest Exposures: A Geologic Study of the Northwest. Mountain Press Publishing Company, Missoula, Montana.
Campbell, Charles D.
1947 Cambrian Rocks of Northeastern Stevens County, Washington. The Geological Society of America Bulletin 59(7):597-612. Electronic document, http://gsabulletin.gsapubs.org/content/58/7/597.short, accessed May 1, 2011.
Sparrow, E., H. Ramsey and L. Poppe
2010 Gardner Cave: Geology. Electronic document, http://ol.scc.spokane.edu/ABuddington/G210Proj/2010g5/geology.html, accessed May 1, 2011.