Castle Butte is an imposing precipice that towers over the Dew Drop Flats north of Kamloops Lake. It projects forward from the line of cliffs that make up the Red Plateau Escarpment, and was formed by a succession of lava flows from an ancient volcanic cone which once existed a short distance to the west.
The flows have given the south face of Castle Butte a layered appearance, and at the top of one of these layers is a natural rock arch. The location of this arch is not well known despite its considerable size, as it can’t be easily seen from the flats below and is not visible at all from above.
The structure has an elongated, oval-shaped entrance about 12 feet wide and 35 feet high, and an upward-curving top which is generally wider than it is thick, giving it a roof-like appearance. Its other opening is much smaller, and is situated at the top of the 25-foot-high nearly-vertical back wall.
There are several different types of arches, each named for the manner in which they are thought to have formed. This one may be a Cave Natural Arch, formed when part of the roof of a cave collapses leaving a portion suspended by the walls of the cave. When
I come to this arch I do feel as if I am actually inside a cave, and I always experience a sense of shelter and protection when there.
On geologic time scales, all arches are short-lived. The rock they are composed of may be very old, but they are not. Any arches in our area only came into existence after the retreat of the glaciers less than 9,000 years ago, and all will one day succumb to the same erosional forces that created them.
To see the Castle Butte Natural Rock Arch for yourself, follow the Tranquille-Criss Creek to the Frederick Road intersection, then follow Frederick Road for 3.3 km. Castle Butte is in plain view to the north. Follow a rough grade west for 0.55 km, then head north on foot toward a large hill on the east side of the butte – the arch is at the top of this hill. There is no actual trail to follow, but a shallow ravine leads straight toward it, and the final section requires a scramble up the side of a chute. It takes effort to get there, but the place is well worth visiting – big arches are rare in the world.
In this view the arch is about 20 feet straight up.
The Rock Arch is a GPS mapped hike in the new guide book, Kamloops Backcountry Hikes available at retailers listed here: http://www.mairibudreau.com/kbhikes