First, A Bit of History
In 1823, the Burlington Bay Canal was proposed as one of a series of waterways which would open Lake Erie to sea traffic from the Atlantic. Local residents supported this proposal as a way of making Burlington Bay into a usable harbour by linking it to nearby Lake Ontario.
Work on the canal began in 1826, and was completed in 1832. A wooden lighthouse was constructed on the canal in 1838 to guide ships to and from the harbour, but in 1856 the wooden lighthouse, along with the light keeper’s and ferryman’s dwellings, burned to the ground from sparks from a passing steamer. The two dwellings were replaced by temporary buildings, and the current Dolostone Lighthouse, and Brick keepers dwellings finally completed in 1858. The new 55-foot tower and brick keeper’s dwelling served until 1961, when the light was deactivated (103 years later).
The 1858 Burlington Canal Main light Lighthouse consists of a slightly tapered 55-foot high circular tower with an iron lantern. Constructed of white dolomite limestone laid in regular courses with a round-arched doorway, it was built by the Scottish mason, John Brown, who was responsible for a series of six Imperial Towers on Lake Huron and Georgian Bay, all still standing.
The Burlington Canal lighthouse was a well-crafted structure, built to endure the harshest weather and withstand the threat of fire. The original lights were a pair of oil-burning lamps with reflectors. At decommissioning (1961) the light had been electrified and was equipped with a third order Fresnel lens, now in safe storage pending restoration of the tower and lantern.
Dolomite: A Mineral and a Rock
"Dolomite" is a word that is used by geologists in two different ways: 1) as the name of the mineral dolomite; and, 2) as the name of a rock known as dolomite, dolostone, dolomite rock, or dolomite limestone.
What is Dolomite?
Dolomite, also known as "dolostone" and "dolomite rock," is a sedimentary rock composed primarily of the mineral dolomite, and is found in sedimentary basins worldwide. It is thought to form through the alteration of limestone by magnesium-rich groundwater (Dolomitization).
Dolomite and limestone are very similar rocks. They share the same color ranges of white-to-gray and white-to-light brown. They are approximately the same hardness, and are both affected by acidification from acid rain and other acid sources. They are both crushed and cut for use as construction materials and used for their ability to neutralize acids.
However, dolomite is slightly harder than limestone, with a Mohs Hardness of 3.5 to 4, and limestone has a hardness of 3. Dolomite is also slightly less soluble in a weak acid solution. Calcite will react (bubble) vigorously, while dolomite produces a very weak reaction.
Uses of Dolomite
Dolomite and limestone are used in similar ways. They are used as an aggregate in roads and other construction projects; kiln-fired in the manufacture of cement; cut into blocks and slabs for use as a building stone like in this Burlington Canal Main Lighthouse; or in some cases used to produce lime, for the neutralization of acid in lands and waters.
Dolomite is often preferred, as its greater hardness makes it a superior construction material. Its lower solubility makes it more resistant to the acid content of rain and soil.
Time to Work
The posted coordinates will take you to a location near the base of the Burlington Canal Main Lighthouse, that was built in 1858.
In order to claim this EarthCache as a find, please send answers to the following questions to the CO at the top of this page.
1) Examine the stone walls closely of the lighthouse. What evidence do you notice (if any) of the weathering effects caused by dilute acid solutions (such as acid rain) on the 160 year old dolostone structure.
2) Compare the weathering on the dolostone lighthouse, to the weathering on the brick lighthouse keepers residence, of the same age nearby. What do you notice?
3) In your opinion, which of the two historical buildings have weathered the years better.
4) What is the average size of the dimension stones used in the construction of the lighthouse
5) Visit the reference point, to read through the historical information on the lighthouse. According to this plaque, where did the dolomite come from, that was used in the construction of this lighthouse.
6) Photos are always appreciated, we would love to see what you saw!
Up-coming Events
Burlington Canal Lighthouse will be celebrating it's 160th Birthday, on Saturday October 20th, 2019 From 10:00 a.m. to 4:00 pm
This free event features guided tours, birthday cake, children’s crafts, prizes, souvenirs, and more!
Source: http://www.bclg.ca/lighthouse_history.htm
https://www.differencebetween.com/difference-between-limestone-and-dolomite/
https://geology.com/rocks/dolomite.shtml