Geology of Sunken Lake
Another interesting glacial feature that only occurs in Black River is Sunken Lake. This lake is unique to many lakes in Nova Scotia in that it is largely spring-fed rather than having water run into the lake from the surface. The lake water is clear and does not have the typical bronze colour water that gives the name of Black River to the main drainage river of the community.
Sunken Lake was formed when a small glacier was left isolated from the retreating and melting main glacier. Glacial gravels were shed and deposited around the perimeter of the ice block during the melting process. The sand and gravel that was trapped in this ice block and shed around the perimeter of the block provided a natural filter for the water making it clear. After the ice block melted only the lake remained with no large surface inlet to the lake and only a small drainage creek in the south western portion of the lake. This drainage creek is mostly active during spring runoff. There was a saw mill located on this outlet for a number of years. This type of lake is known geologically as a Kettle Lake. The melt waters from the Sunken Lake ice flowed eastward joining the melt waters from the main glacier in the Bentley Meadow area contributing additional water to the Schofield Brook drainage system. Residents of Black River always said that Sunken Lake has no bottom and the true depth of the lake is not known. There is truth in this statement and confirms the Geological origin of the lake as an ice block hole surrounded by glacial gravels and sand shed from the ice during the melting process of the ice block.
This lake is on the highest part of the South Mountain and on some topographic maps was named Summit Lake, but locally the lake is Sunken Lake.
For many years ice from Sunken Lake was harvested and in the authors memory was stored in the Clifford Long ice house buried in sawdust for year-long use. This ice was the source of ice for making ice cream during the hot summer months and for those who owned an ice box before the days of refrigerators. The clear clean characteristics of the lake water made ideal ice.
- Ron Buckley, from a draft of "Geological History of Black River, Kings County, Nova Scotia"