Cliff Park EarthCache
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Cliff Park: Volcanic Outcrop
Standing at 2260 feet above sea level, this volcanic outcrop was used by the Spokane Tribe as a lookout. On a clear day you can see as far as the Little Spokane River and Mount Spokane. The park was formed in 1908 and included only 4.2 acres. Minimal improvements were made including steps, paths, seats, and a drinking fountain. A request was made to build a tower at the top of the parapet, but that decision was deferred in the 1913 and the tower was never erected. Today the park looks much as it always has, except that the trees that have grown up limiting some of the once-sweeping views. Today, people still climb to the top of the lookout for a view of the city and the surrounding area. The trees are a little taller, but the view is still amazing.
Cliff Park Circa 1910 on a Picture Postcard
Columbia Plateau
The Columbia River Basalt Group, also known as the Columbia Plateau, covers most of Eastern Washington and surrounding areas. Lava began flowing in the Columbia Basin about 17 million years ago and continued until about 6 million years ago. In all, there may have been 300 individual outbreaks. Each lava flood was separated by thousands of years in which nothing happened. Extrusive igneous rocks (molten, liquid following, rocks exposed to the air), also known as volcanic rocks, are formed at the crust's surface. Extrusive igneous rocks cool and solidify quicker than intrusive (underground) igneous rocks. The molten magma, which is brought to the surface through fissures or volcanic eruptions, is known as lava. Extrusive igneous rock formed lava flows, lava sheets and lava plateaus. The lava formation at Cliff Park is an example of basalt rock formed from igneous extrusions.
Shape and Color
At times some lava flows solidify to form long, fluted, or polygonal basalt columns. The columns form as the basalt contracts while cooling, forming cracks. Once the cracks develop they keep growing. The growth is perpendicular to the surface of the flow.
The color of basalt rock varies from light tan to dark black. The longer basalt is exposed to the air the lighter in color it is.
Lake Missoula Flood
Cliff Park is a 4 1/2 acre park surrounding a volcanic outcropping that is nearly an acre in size. The outcropping would have been exposed at the time of the Lake Missoula Flood which occurred about 15,000 years ago at the end of the latest ice age. The Lake Missoula Flood ran fast and furious when the ice dam melted away causing a flood over 500 feet deep in the Spokane River valley. The torrential water erosion from the flood likely washed away dirt and other rock debris leaving this lava outcropping to stand sentinel over the city.
Logging Requirements
To log this EarthCache you must physically visit the coordinates and send me answers to the following questions. Do not post your answers with your log and do not post spoiler photos.
1) Do you see any evidence that the basalt outcropping formation contains any long, fluted, or polygonal columns? If so, which side (north, south, east or west) of the rock displays them best? Explain how they might have been formed.
2) What is the predominate color of the of the basalt found in this formation?
3) The basalt columns range in diameter from ______feet to ______feet?
4) Estimate the height of the volcanic outcropping above the surrounding park area.
Additional Hints
(No hints available.)