Mason Lake is a natural elongated lake south of Belfair, Washington, United States in Mason County and is known for power boats, jet skis, and water skiing. Mason Lake is one of the largest lakes in Mason County and is open year-round for fishing. It was named after Charles H. Mason, the first secretary of Washington Territory. The geocache is located at the only public boatramp on the lake.
Mason Lake is approximately 1000 acres in size and four miles long. Its maximum depth is 90 feet (27m) and the average depth is 48 feet (15m). The lake is approximately 5 miles long and 0.75 miles wide with 10.9 miles of shoreline. The surface elevation is 194 feet (59 m).
Mason Lake is home to a large amount of wildlife, including: bald eagles, ringed-necked pheasants, robins, mallards, diving ducks, canvasbacks, ruddy ducks, killdeer, great blue heron, and otters. Fish include: rainbow trout, largemouth bass, yellow perch, brown bullhead catfish, rock bass, salmon, and northern pikeminnow.
Mason Lake is located within the Mason Lake quadrangle, near the center of the Puget Lowland. This area is covered by a thin layer of glacial drift over layers of glacial and nonglacial sediments, exceeding 500 feet of depth in places.
The sediments brought by glaciers into the Puget Lowland may be from any of three different source regions:
- Northern provenance (the Coast Range of British Columbia): predominant source for rock fragments and grains from granitic and metamorphic rocks.
- Cascades provenance (Cascade Range of Washington): most likely source if the sediment contains andesitic volcanic rock fragments and glass in addition to granitic and metamorphic rock fragments.
- Olympics provenance (Olympic Mountains): predominant source for rock fragments and grains from basalt and mafic rocks
Lakes can be formed in many different ways. Some of the main types of lakes include:
- Glacial lakes formed by glaciers carving depressions in the Earth’s surface, which are then filled by melting ice. Example: the Great Lakes in the U.S. and Canada. There are many sub-types of glacial lakes, including cirque lakes, moraine lakes, and kettle or pothole lakes.
- Tectonic lakes that form at fault lines where plates meet. Lakes can form when adjacent plates separate at fault lines or at points of tectonic upwarping. Example lake: Lake Baikal.
- Lakes formed due to volcanic activity, including when the roof of a volcanic crater caves in, forming a crater lake. For example, Crater Lake in Oregon.
- Lakes formed as a result of river movement, including when rivers erode their shoreline, when lakes form at the base of a waterfall, and when lakes form in depressions on a river floodplain.
- Man-made lakes formed as a result of intentional or unintentional damming of a river. Example: Lake Mead, formed by the creation of Hoover Dam.
Sources:
Logging requirement for this cache (please send via direct message / do not post answers in your log):
- Looking around at the rocks and sediment at this location and referring to the information above, what do you think the possible origin is for the sediment at this location? (Olympics, Cascades, and/or Northern)
- Referring to the information above regarding different types of lakes, what is your hypothesis regarding how Mason Lake was formed? Why do you think that?
Optionally, post a picture of yourself at the cache location.
Congratulations to sheppard4 for FTF!