The maar lake that you will observe in Stage 1 is on the private Buckingham Golf and Country Club. However, you will not have to enter the country club. Rather, take Westlake Drive from the country club parking lot, around the lake to a good vantage point above the lake where you can observe its shape. Good parking for one or two cars is about 100 yd away. Stage 2 is on the shoulder of the road opposite a road cut for you to make observations regarding the fragmentary rock forming a maar.
You are in the Clear Lake Volcanic Field. The most prominant features in the area are Clear Lake and Mt. Konocti with its five volcanic peaks. But smaller features are easier to grasp when they can be observed in their entirety. Such is the case with this maar lake. A maar is a broad, low-relief crater formed when groundwater comes in contact with with hot lava or magma. The water flashes to steam causing what is called a steam or phreatomagmatic explosion expelling a large amount of shattered rock. Most maars commonly fill with water to form natural lakes. They have low rims composed of a mixture of loose rock fragments. There are several maars around Clear Lake, including some at the edge of the lake forming a scolloped shoreline.
At Stage 1 you are looking down on an entire maar lake called Little Borax Lake. It got its name from the borax industry which originated here in Lake County. Borax (hydrated sodium borate) became a popular cleanser in the 19th century. Between 1868 and 1873 the entire nation's supply came from Lake County.The first discovery was at (big) Borax Lake (see GC7FED8). Later it was discovered here. The resource was soon depleted, however, and it wasn't long before Lake County's role in the history of the borax industry was eclipsed by major discoveries in Death Valley in the 1880s.
Stage 2 is a road cut dramatically showing the deposits of fragmented rock forming one of the many maars in the area. The layers of rock you see are called surge deposits. They consist of a mixture of Clear Lake mud and fragments of volcanic rock that spattered out of the center of the crater during eruptions. If you could cut into the ground around Little Borax Lake, you would find similar deposits.
LOGGING THE CACHE
You can log the cache as Found. Then message or e-mail me the answers to the following questions. DO NOT put your answers in your log. If I do not receive your answers, your log will be DELETED.
1. What is the shape of Little Borax Lake?
2. If the water level is low in Little Borax Lake you may observe a white deposit around the edge of the lake. What is this likely to be?
3. What causes the explosive force which forms a maar?
4. What is the average size of the rock fragments in the maar deposit at the road cut?