Lake Fletcher's dam
Aug. 13th, 2003 01:18 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
vaneramosAt the lower end of Fletcher Lake is a manmade dam. About 10 feet high, it exhibits the sole apparent purpose of keeping the lake's water level stable. Fletcher is about 1,300 feet above sea level and near the top of the local watershed. In high summer there is not much water overflowing, perhaps two or three gallons per second.
This part of Ontario lies near the southern edge of the Canadian Shield, a vast sheet of Precambrian rock covering more than half of Canada, most of Greenland and Northern Michigan, Wisconsin and Minnesota. It was formed about 500 million years ago, and is the largest exposed landform of this age on Earth. It has been repeatedly uplifted and compressed and consists mostly of rolling hills. Repeated glaciation has left only thin topsoil.
Most of the bedrock around Lake Fletcher is pink granite, but a nearby extrusion of minerals has been quarried. It sat idle for many years and we used to collect rocks there. It contains white quartz, pink feldspar, biotite and some other minerals. Two years ago, a new owner started operating it again, and posted signs forbidding the unlawful removal of materials.
The quarry isn't far from the dam. If you look carefully in the streambed below, you can still find interesting minerals, particularly plates of black biotite mica. The river has worn the chunks smooth, but they easily split apart, exposing smooth surfaces shinier than glass. You can peel off thin, pliable, transparent sheets.
We visited the dam on August 4. While Mark picked through stones below the dam, Marian, Brenna, Bob and I explored the course of the stream. If we had all afternoon and the energy to cross rough terrain, we could follow it for miles through marshes and forests. It eventually drains into a larger body, Kawagama Lake.
Mark and Bob selected some interesting rocks to take home for their garden.
Above the dam
Pickerel-weed
Marian following the stream
Brenna at the dam
This part of Ontario lies near the southern edge of the Canadian Shield, a vast sheet of Precambrian rock covering more than half of Canada, most of Greenland and Northern Michigan, Wisconsin and Minnesota. It was formed about 500 million years ago, and is the largest exposed landform of this age on Earth. It has been repeatedly uplifted and compressed and consists mostly of rolling hills. Repeated glaciation has left only thin topsoil.
Most of the bedrock around Lake Fletcher is pink granite, but a nearby extrusion of minerals has been quarried. It sat idle for many years and we used to collect rocks there. It contains white quartz, pink feldspar, biotite and some other minerals. Two years ago, a new owner started operating it again, and posted signs forbidding the unlawful removal of materials.
The quarry isn't far from the dam. If you look carefully in the streambed below, you can still find interesting minerals, particularly plates of black biotite mica. The river has worn the chunks smooth, but they easily split apart, exposing smooth surfaces shinier than glass. You can peel off thin, pliable, transparent sheets.
We visited the dam on August 4. While Mark picked through stones below the dam, Marian, Brenna, Bob and I explored the course of the stream. If we had all afternoon and the energy to cross rough terrain, we could follow it for miles through marshes and forests. It eventually drains into a larger body, Kawagama Lake.
Mark and Bob selected some interesting rocks to take home for their garden.
Above the dam
Pickerel-weed
Marian following the stream
Brenna at the dam
