This earth cache requires you to use a canoe, kayak, or raft to head down the very narrow and shallow Rock Creek. The rock arch is ~1 mile from the bridge where you can put in. The land around the creek is privately owned so you will have to stay in your boat as you approach the rock arch.
You can set your boats in and park at the bridge just south of the cache site (Hole in the Ground rd). The landowners have given permission to use this area to put in and park. Please do not block any gates with your vehicles.
The 'Rock Creek Arch' is one of the only natural rock archs in all of Washington State. A natural arch or natural bridge is a natural geological formation where a rock arch forms, with an opening underneath. Most natural arches form as a narrow ridge, walled by cliffs, become narrower from erosion, with a softer rock stratum under the cliff-forming stratum gradually eroding out until the rock shelters thus formed meet underneath the ridge, thus forming the arch. Natural arches commonly form where cliffs are subject to erosion from the sea, rivers or weathering (subaerial processes); the processes "find" weaknesses in rocks and work on them, making them larger until they break through. This natural arch resulted from an underground crack which extended to the surface of a rock terrace formed by a resistant lava flow. Once the process was started, erosion did the rest. On the left of this bridge is the beginnings of a second such arch so that you can understand better how it actually happens.
If you are up for an adventure, keep heading north on the creek to Bonnie Lake (~1 miles). The lake is magnificent with huge canyon walls and a large island. There is no road, houses, or any other way to this lake, so you will very likely be the only ones. At the time of this posting there is a cache on the bridge where you set off, and 2 more on the island on Bonnie lake.
To log this earth cache, you must go to coords listed email me answers to the following questions.
1: Roughly, how tall is the opening in the rock arch?
2: Roughly, how wide is the opening in the rock arch?
3: How many people were in your group today and what was the weather like?
4: What water vessel did you use to make it up the creek to the rock arch?
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