Friday 7 November 2014

A Contest to Find the Largest Glacial Erratic in Lanark County

In 2016  the Town of Perth,  Tay Valley Township, Drummond North Elmsley Township and Beckwith Township will celebrate the 200th Anniversary of the founding of the Perth Military Settlement and  the arrival of the first settlers and War of 1812 veterans to our area.

I’ve been wondering for some time now how to tie this in with Ontario Highland Tourism’s promotion of Lanark County as a geotourist destination.    After months of thought, and a few bottles of red wine,  I’ve decided that what Lanark needs is an annual contest to find the largest glacial erratic in Lanark County that has not previously been mentioned on this web site or in a scientific report or that has not previously won a prize in a similar contest.    The first contest would start in November, 2015 and will end in November 2016, with the winner and the erratic announced in December, 2016.

The beauty of this contest is that almost everyone in Lanark is blessed with glacial erratics left by the retreating glaciers.  Some farmers may use a different word than “blessed” to describe the boulders in their topsoil, but those would be the ones without an understanding and appreciation of Lanark’s glacial history.    As mentioned in previous postings, about 79 thousand years ago the Wisconsin glacial period  started, glaciers formed, advanced and retreated, and at their maximum extent covered most of Canada and extended down into the United States. Lanark County was covered by a glacier two kilometers in thickness. When the glaciers finally retreated from Eastern Ontario about 11,000 years ago they left behind ample evidence of their former presence in Lanark County including eskers, glacial till, glacial striae and glacial erratics – all to be admired and  appreciated.  

I have not yet finalized the rules, categories, number of judges, entrance form and waiver, but expect that to get the contest up and running over next summer.   The reason that I publicize it at this point is that I’m open to suggestions and welcome the help of everyone that wants to get involved.   (It is not that I’m desperate for an article for a blog posting.)

In addition to the prize for the largest erratic, I propose prizes for the winners of a number of categories:
- largest erratic on an operating farm or maple sugar bush
- largest erratic at a sand or gravel quarry
- largest erratic within a town’s boundaries
- largest erratic other than on an operating farm or maple sugar bush, at a quarry or within a town’s boundaries
- best use of an erratic in garden landscaping

There will necessarily have to be some exclusions, including.
- not underwater
- verifiable
- not previously moved.

For the benefit of those that have recently moved to Lanark County from the city, I note that
where the glacial erratic occurs with other boulders in row along a fence line, this is an obvious exclusion as the erratic has been previously moved.     I expect that some whiners are going to say that many large erratics along fence lines are too heavy to have been moved.  However, men were men and oxen were oxen when Lanark was first settled.  No stone that I have seen  is too large not to have been moved by the first settlers.     (I have to admit that I had considered adding a category ‘largest erratic along a fence line’ in order to be as inclusive as possible, but decided against this as it rewards those that have destroyed their geologic heritage.)

In addition, no one can enter that is related to one of the persons running the contest.  This is an obvious exclusion as I have some large glacial erratics on my property, and I would not want to be accused of running a contest, or finagling the categories,  merely so that one of my erratics could win.

I had considered running this contest in conjunction with the Annual Perth Fair that is held the first weekend in September, requiring that all entrants bring their erratics in for judging, much the same as people weigh in their pumpkin and gourds for largest pumpkin contests.    However, most erratics should not be moved, as this affects their scientific value.    While you would like to think that people would replace their erratics exactly where they take them from, this is unlikely to be the case.   Also, I’ve talked with some of the people that run the fair, and there is a fear that people that loose would just leave their erratics for the operators of the fair to dispose of. I see that as a real concern, and not raised merely to disassociate themselves as far as possible from the contest.  Who wants to be left with five ton boulders lying all around the place?

I suspect that some will argue that this contest unfairly gives those of Irish descent an unfair advantage.  I make that statement because eight years ago when I mentioned to my dentist in Ottawa that I had moved to Tay Valley Township in Lanark County he told me that he had been born and raised in Lanark County,  that the English had received the good land and the Irish the rocky land.  Memories run deep in Lanark County.   His family was Irish .  I can only say ‘play the hand that you are dealt.’   If this contest  does give those of  Irish descent an unfair advantage, then it is poor compensation for having farmed rocky land for 200 years. 

Some will suggest that I’m just too lazy to get out there to find the erratics myself, or that I’m just trying to drum up readers for my blog.   I have no answer for that other than to say that I have lots of glacial erratics on my own property, and I’m not interested in a reader that reads my blog only because he or she wants to win the contest.

I should mention that not all boulders are glacial erratics.  Long time residents of Perth will recall the large black boulder that for many years was a fixture on Wilson Street in front of the Perkins GM building.   That was not an erratic.   It was a gabbroic boulder with too many fresh surfaces to have been polished and transported by a glacier.   Another clue is that it was resting first  on asphalt and later on paving stones. The glaciers retreated from Perth thousands of years before that asphalt was laid down or the paving stones put in place.

A further exclusion is that the rock must not be the same as and in contact with the underlying rock.   In addition, the contest organizers will exclude all rocks that have just broken off an outcrop and rolled down the hill.   I also fear that if the contest takes off, some will be sandblasting rocks to make them look like rounded and polished glacial erratics.   Accordingly, three geologists will be needed  as scrutineers and judges to determine the winner, plus one lay person in the event of a tie.   Some will ask how you can possibly have a tie with three people as the judges.   The answer is that some geologist have more than one opinion on a subject, and some hedge their bet.   For example, Who hasn’t looked at a granitic boulder and wondered if it was granite or merely granitic gneiss?  Who hasn’t looked at an outcrop of sandstone and wondered whether it is Potsdam sandstone or March sandstone, and does anyone really care which it is?
   
Above I mentioned that excluded from the contest will be glacial erratics that were previously mentioned on this web site, in a scientific report or that have previously won a prize in a similar contest.   Those exclusions are necessary to prevent numerous people from entering the same erratics.   For those that have not read each of my blog postings, this excludes both (a) the glacial erratic, then known locally as Samson’s Shoulder Stone (and now sadly forgotten), that can be found about 11.26  kilometers east of Perth along County Road 10 (the Franktown Road if you are heading to Ottawa, and the Perth Road if you are headed to Perth) reported on in 1932  by Dr. Morley Wilson of the Geological Survey of Canada that was featured in Volume 46  of the Canadian Field-Naturalist and (b) the glacial erratics at Wheeler’s Pancake House and Sugarbush. 
           
I’ve decided against offering a monetary prize, which would only pit neighbour against neighbour, husband against wife, and fathers and mothers against their children.   Instead, the prize will be a certificate,  a photograph of the winner and his/her erratic  published in the Perth Courier, and the photograph of the annual winner on a plaque kept at the Perth Museum.   I can see the plaque now:  2016 - a photograph of a granitic or gabbroic boulder from Lanark Highlands. 
   
I realize that there could be a problem with the contest ending during deer hunting season.  My wife has pointed out that this automatically disqualifies half of the male population of Lanark County, as men put things off to the last minute and will be too busy during deer hunting season to enter.   My answer to that is that women hunt.   Some hunt deer, some hunt for men and some are always on the hunt for new pair of shoes.     Women hunt.  I should note in passing that while I would normally assume that one of my wife’s comments directed at all men is somehow directed at me,  I don’t hunt.

Every contest requires a mathematical, time limited, question in order to take it out of the anti-gambling provisions of the Criminal Code.   I propose:   What is the weight of your glacial erratic, to the nearest ten kilograms, assuming that most common rocks composed mainly of silicates weigh about 160 pounds per cubic foot?    Some people will complain that this is a trick question designed to catch those that don’t realize that both pounds and kilograms are mentioned.  Others will complain that it is a trick question designed to catch those whose erratics are comprised of marble or limestone (both carbonates, not silicates). Some will complain that we should never have adopted the metric system.   Others will just complain.   However,  no one said that it had to be an easy question.    To overcome any concerns I propose giving each entrant two tries over two days.

Of course, that mathematical question will require that all entrants sign a Waiver acknowledging that the contest organizers  (a) do not encourage,  condone or recommend the lifting of bounders to determine their weight and (b) are not responsible for medical or other expenses where the entrant tries to weigh the erratic.   Other parts of the waiver still have to be drafted.

When to hold the awards ceremony?   The obvious  date is December 24 to commemorate the signing of the peace treaty that ended the war of 1812 (the Treaty of Ghent was signed on December 24, 1814) as this led to the founding of the Perth Military Settlement.   However, my wife has reminded me that I am usually busy on that day finishing my Christmas shopping.    I’m open to suggestions.

There is another obvious issue: When in November to close the contest?  For the first year I have arbitrarily chosen November 11th, because it  is a day that is easy to remember and because it commemorates the Battle of Crysler's Farm in Lower Canada.  What better day then to commemorate the decisive British and Canadian victory on November 11, 1813 which convinced the Americans to abandon their campaign down the St. Lawrence River!  However, many Lanark County residents have 11th of November booked each year, and that ceremony is the more important one.   For subsequent years I propose that 31 sequentially numbered counters be placed in a bag and that each year’s winner draw the date for the next year,  with the contest to close on the day drawn.   I do realize that there are 30 days in November.  Where number 31 is drawn the contest will not be held the following year.  Some will complain that it should end on the same day each year so people can plan.   Some will complain that if it is not held one year, then it is not an annual contest.  However, it is, after all, an erratic contest. 

Christopher Brett
Perth, Ontario

Addendum (November 11th): 
      The Town of Perth may have a connection to the Battle of Crysler’s Farm.  In front of the Court House in Perth can usually be found two brass three-pounder light infantry cannons.   (One is currently missing, and is hopefully just out for repair.)  The cannon on the left (as you are looking at the Court House, and the one that remains) bears the inscription ‘J. & P. VERBRUGGEN, FECERUNT A 1775.’   The other cannon is reported to bear a nearly identical inscription.   The word 'fecerunt' is a Latin word that translates into English as 'made, constructed, cast.'   The cannons were undoubtedly cast at the Royal Brass Foundry at Woolwich, England where  Jan Verbruggen and his son Pieter were the master founders from 1770-86.   The cannons are said to have an interesting history: they were captured by the Americans from the British at the Battle of Saratoga, and were recaptured by the British regulars and Canadian militia at the Battle of Crysler’s Farm.   Later they were presented to the Perth Military Settlement.
    



Tuesday 4 November 2014

Layering in the Mealy Mountains Anorthosite Complex, Labrador

In my last posting I mentioned that I had seen spectacular layering in anorthosite intrusions in Labrador.  Below are photographs that I took of layering in the anorthosite plutons that form the Mealy Mountains in Labrador.  The person that is the scale in the photographs is Dr. Ron Emslie of the Geological Survey of Canada, who was about average height for a world renowned expert on anorthosites.
















Ron described the layering as follows:
“Within leucotroctolite, leucogabbro and anorthosite, igneous mineral layering on a scale of 1 cm to 10 m, or more, is common (Fig. 33. 2). Where rock exposure is good, layers or layer contacts can be found on most clean subvertical rock surfaces more than a few metres high. In leucotroctolite the mineral layering involves differences in proportions of olivine and plagioclase,
whereas in leucogabbro and anorthosite, variations in pyroxene and plagioclase proportions are the chief cause. In addition to mineral layering, manifestation of layers is due to differing plagioclase grain sizes and shapes and in some cases, plagioclase colour particularly in leucogabbro and anorthosite. Dark layers in some anorthositic rocks were found to consist of darker coloured plagioclase than that in the enclosing host rock. Such "dark plagioclase" layers were evident in some places even where the enclosing rock contained a noticeably higher proportion of ferromagnesian minerals. Large areas of the complex have relatively consistent layering attitudes. For example, the northwestern part of the complex has dips to the northwest
and west at angles less than 30 degrees. Other areas have remarkably discordant layer attitudes over short distances and sometimes even within the same outcrop. Such discordance seems to be a primary igneous feature of the crystal accumulation process and is not due to superimposed deformation.”

(Emslie, R. .F (1976), Mealy Mountains Complex, Grenville Province, Southern Labrador,
Report of Activities Part A; Geological Survey of Canada, Paper no. 76-1A; p. 165-170
http://geoscan.nrcan.gc.ca/starweb/geoscan/servlet.starweb?path=geoscan/fulle.web&search1=R=123988
http://ftp2.cits.rncan.gc.ca/pub/geott/ess_pubs/119/119844/pa_76_1a.pdf )


Christopher Brett
Perth, Ontario

Suggested Readings

Emslie, Ronald F.  (1975),  Nature and Origin of Anorthosite Suites, Geoscience Canada, Volume 2, Number 2, pages 99-104
http://journals.hil.unb.ca/index.php/GC/article/view/2912
   
Emslie, Ronald F. (1980) , Geology and Petrology of the Harp Lake Complex, Central Labrador- an example of Elsonian Magmatism.  Geological Survey of Canada, Bulletin 293, 136 pages
http://data.gc.ca/data/en/dataset/96d2a3bc-c79d-57f1-8169-24e01d431893

Hamilton, Michael A. , Scoates, James S. and Rämö, O. Tapani  (2010)
The Petrology of Anorthosites, Related Granitic Rocks, and UHT Assemblages: a Tribute to Ronald F. Emslie, Can Mineralogist, volume 48, pages 705-710
http://canmin.geoscienceworld.org/content/48/4/705.full