PLEASE NOTE THAT THIS PARK IS CLOSED FROM SUNSET TO SUNRISE.
The Skystone is an andesite glacial erratic boulder in Bonney Lake, Washington. It is located about one mile south of the former Naches Trail, a historical trail used by Native Americans and early settlers. The Skystone was apparently rediscovered when a suburban housing development was begun in 1999. The stone measures 4.5 feet high and 12 feet across and features carved stone steps to the top. The pits, or holes on the top and side, were created by local American Indians and are in perfect alignment, indicating the summer and winter solstice sunrise and sunset. Other pits point directly to Mount Rainier, Mount St. Helens, and Mount Adams. The area where the stone sits used to be a prairie. From that vantage point, the view of Mount Rainier would have been breathtaking at winter solstice and on a clear day, the viewer would have been able to watch the sun climb up the side of the mountain to crest at the summit.
Logging tasks:
- Do you think the Skystone is more prone to erosion or weathering? Why do you think so?
- What weathering processes do you detect on the Skystone? Explain your answer.
- Compare and contrast the man-made pits on the stone's surface to erosion or natural weathering.
- Explain why this stone may have been selected for its use by the local tribes.
- Take a picture of you, or an item containing your geocaching name, with the stone in the background and include it in your log.
Send your answers to questions 1. thru 4. to the cache owner. Please do not include them in your log.
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location and then transports it to another location where it is deposited. Eroded sediment may be transported just a few millimetres, or for long distances.
Weathering which is the deterioration of rocks, soils, and minerals (as well as wood and artificial materials) through contact with water, atmospheric gases, sunlight, and biological organisms. While weathering occurs in situ (on-site, with little or no movement), erosion involves the transport of rocks and minerals by agents such as water, ice, snow, wind, waves, and gravity.
Weathering processes are either physical or chemical. Physical weathering involves the breakdown of rocks and soils through such mechanical effects as heat, water, ice, and wind. Chemical weathering covers reactions to water, atmospheric gases, and biologically produced chemicals with rocks and soils.
Water is the principal agent behind both physical and chemical weathering, though atmospheric oxygen and carbon dioxide and the activities of biological organisms are also important. Biological chemical weathering is also called biological weathering. The materials left after the rock breaks down combine with organic material to create soil.
Sources: Wikipedia; Teresa Herriman (April 30, 2009), "Artifact rests in housing development", Bonney Lake Courier-Herald; Gore, Pamela J. W. "Weathering", Georgia Perimeter College.