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Finally Reached That Exposure- Credit River by Streetsville


JUAN EMMANUEL

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Yesterday, after countless trips and exploring at the same old spots on the Credit River in Mississauga, Ont., I finally mustered the courage to go and wade on the water to an isolated exposure out the Georgian Bay Formation at Streetsville, Mississauga. I wanted to collect fossils that were not worn out as these were all I was finding in my old spots. I have been setting my eyes on this exposure from the other side of the Credit River for some time now ever since I started collecting along the Streetsville area and it could possibly harbour fresh material.

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The temperature of the afternoon was around 16-20 degrees Celsius so the water was not chilly as I was expecting it to be. I crossed the water barefoot with the water reaching up my knees at this tributary that separated the exposure from the main path. The Credit has many tributaries flowing and where the these tributaries converged the river, many exposures can be found along these places.

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After crossing I reached the other side without slipping on the slimy bottom. The exposure had thin footing for exploration but I was able to walk back and forth without slipping onto the water.

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Like the other spots with worn out material the place is also riddled with corals except this time the corals are not that worn out.

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Some of the corals were ridden with algae and have mud on them. The mud can be washed off but the algae is a bit tricky to remove. Maybe by hydrogen peroxide perhaps?

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Here are some of the thick limestone interbeddings. I have never seen such thick limestone beddings anywhere in the Georgian Bay Formation yet. These were more than 2 ft thick and an interbedding like this does not occur in Mimico Creek or on the Humber River.

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I used a $20 dollar bill as I did not have a ruler with me.

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Nice corals!  It's worth trying the peroxide on the algae; I have not done that myself.

 

Don

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Below is a limestone ridden with corals.

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There were plenty of corals, Prismostylus, and bryozoans. There were brachiopods but these were not that obvious. Below are some unidentified brachiopods.

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Pieces of hashplates can be found everywhere, with many bits of the Prismostylus (aka Tetradium) as well. I believe the most abundant corals were the Favstella alveolata.

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Here is an interesting association of Prismostylus and Favistella on a piece of limestone that I chose to keep. I'm just planning on how to remove the algal growth on it.

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Here is what I believe what is called a Beatricea sp. sponge. This specimen is a partial.

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What I found interesting is that some of the corals were embedded in shale. The corals found in shale can be cracked with ease to reveal the inner structures of the coral. The specimen above I believe is a Favistella alveolata.

In hunting this area I did not smash any rocks nor did I bring any tools with me. I only did surface collecting and, wishing to respect the integrity of the site, did not think at all of smashing or disturbing any of the natural setting of the rock outcrop. The site is in full view across from a park and I did not wish to draw attention to the activities I was doing from people passing by. By the end of my exploring at the exposure (I think I explored the place for nearly 2 hours), I took a few specimens that I thought were interesting as the Prismostylus, Favistella and the bryozoans were abundant.

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Good report, Juan.

I've never been able to collect Paleozoic stuff like that myself, but thanks to you and other members I've come a ways since school days reading about them in textbooks and fossil guides in the library...

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Here is an excerpt of what W.S. Dyer wrote on page 53 of his "Stratigraphy and Paleontology of the Credit River Section" about these layers: 

"Columnaria Reef.—The Meadowvale member begins with the conspicuous Columnaria reef, in which Columnaria alveolata, Tetradium approximatum, and Stromatocerium huronense are very abundant. Columnaria calicina is also present but is not so abundant as the foregoing species. Tetradium approximatum assumes at times very large proportions, one specimen being found with a diameter of 18 inches. In addition to the above coelenterates, the two bryozoans, Rhombotrypa quadrata and Constellaria polystomella, are very abundant. It is strange that these two species, which in other areas are found in nearly all of the divisions of the Richmond, should be found only at this horizon on the Credit. The following fossils, also, are found in the Columnaria reef: Hallopora cf. onealli, Homotrypella hospitalis, Hebertella occidentalism Platystrophia clarkesvillensis, Zygospira modesta, Byssonychia sp., Opisthoptera fissicosta, Lophospira bowdeni, Lophospira tropidophora, Cyclonema sp., and an indeterminable species resembling Fenestella. Foerste lists from this horizon Calapoecia cribrijormis and small specimens of Streptelasma rusticum. The reef varies in thickness from 18 inches to five feet and consists chiefly of limestone, but thin bands of shale are also present, and in many cases the corals lie embedded in shales."

From reading his work I have a feeling that I'm coming close to the places he observed and saw. 

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Congratulations on finding such stunning corals - I'm glad you had a great day out!

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That, sir, is a killer spot.  To the bold go the spoils!!!

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Great report and pics! Congratulations on finding this location. Thanks for sharing your adventure.

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I like Trilo-butts and I cannot lie.

 

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A few days later and I get to the other end of the exposure and this time I got to check out the series of limestones and shales... The short episodes of light, re-occuring rain and thunderstorm warnings of today did not deter me from hunting. I slipped several times and nearly hit myself on some rocks thanks to some algae on the banks; poison ivy littered the end and are in full leaf; and insect larvae fell on my hair without me noticing 'til 1 hr later. But I guess when you realize that no one else has claimed the site (except for anglers that use the site for fishing), the place is your oyster.

The limestones are quite thick. Below is a panoramic view of the exposure's end before it disappears down river.

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Some more hauls... I guess no ones been here!

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Stromatocerium colony nearly a foot wide. This specimen is only a partial.

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Stromatocerium bits on the limestone.

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I wonder why the Stromatocerium are abundant? I even collected specimens of a stromatoporoid encrusting a Prismostylus.

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Exposure pics. This was only observable at the end of the site. Down river the bank goes flat again.

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You guys, I might end up having some extra coral material so keep your heads up, I might end up trading some away...

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Juan, I really enjoyed reading your report and examining all the pics! Several weeks ago I found a few specimens like those identified in your report as Favistella in a Mississippian Hartselle Sandstone outcrop in northeast Alabama. I've been going back and forth on the identification. Also interested in the best way to remove the algae growth. So, your report was both enjoyable and helpful!! Thanks! :)

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