Ottawa, River Plant Fossil -After flood of 2019

[Metawatch]

This rock weighing in at a hefty  2.5 kilo  (shale ?) is completely surrounded by plant fossils that actually wrap around the rock itself. I.E. As to indicate that a pre-formed rock fell into the water and crushed the surrounding plants and caused them to fold around the surface while embeddeding itself in the environment that encourage fossil formation. 

 

I really don't have a  clue as to its makeup or origin (Above speculative).

 

It should should be noted that it was found on the ground surface after the flood where an adjacent embankment wall suffered severe weathering due to the flood of 2019.

 

Latitude: 45.5492085725
Longitude: -74.3639289159

[Rockwood]

14 minutes ago, Metawatch said:

is completely surrounded by plant fossils that actually wrap around the rock itself.

What makes you think they are plant fossils ?

[Metawatch]

Considering you have 5,200 posts to my one post, I'll let you tell me what you think they are. To my naive eyes, they look like crushed aquatic plants . Please feel free to provide me more a more insightful accurate perspective. 

[Rockwood]

The day I think I can't learn something I should quit.

All I can say now is that they don't look like fossils to me.

[Kane]

It is possible these are ichnofossils such as worm burrows in heavily weathered rock. I know the Ottawa River (at least in Ottawa and region) has an abundance of Ordovician-aged sedimentary rock, with some isolated Quaternary deposits.

 

Differential weathering will mean certain features will not weather as quickly due to mineral content, which may account for the appearance of this piece.

[FossilDAWG]

This rock is limestone with areas of silica, which follow cracks or planes of weakness in the rock and may also be replacing burrow structures (trace fossils).  This lithology is common some of the lower limestone formations in the Ottawa valley, such as the Gull River and Rockland formations.  The limestone can be dissolved by acid, such as acidic ground water, whereas the silica is quite resistant and so ends up standing out from the rock.  In places fossil shells have also been replaced by silica, so they can weather completely free from the rock or be released by dissolving the limestone in dilute acetic acid (vinegar) or hydrochloric acid (= muriatic acid from hardware stores).  [Word of caution: if working with acid wear protective clothing, gloves, eye protection, and work in a well ventilated area, ideally a fume hood or outdoors.  To dilute the acid, always add the acid slowly to water and avoid splashing.]  I collected and prepared such fossils from several sites in the Ottawa valley, especially near Pakenham, Braeside, and the Ottawa River near Pembroke.

 

Don

[Metawatch]

LOL....So my funny looking Plant fossils are Silica cracks in a limestone rock that could have been created by "trace fossils.

Looks like thanks to FossilDAWG we are homing in on this creatures origin. (Thanks !)

 

Found another post with a somewhat similar type of rock  (Rockland - Found about 50 km from my location ) although the surface marking vary significantly.

(I included one more photo of mine below for comparative purposes.)

 

 

Of Note: One corner is showing sighs of oxyidation (Rust like) similar to picture above, although the material is not particularly sensitive to a kitchen fridge magnet...

 

So if this is yet another sample of the Rockland (Ottawa River Shale) it would be from the https://en.wikipedia.org/wiki/Ordovician#Flora Ordovican period (~ 400 million) years ago...

[Metawatch]

Another interesting article about the Specifics of Pointe Fortune. https://pdfs.semanticscholar.org/bbb0/3086bf7c2e0a674366ce45100b2e8003be48.pdf?_ga=2.47843815.1141972257.1565196258-1329900508.1565196258

 

[Metawatch]

I think this formation is actually from the Carillon Formation (As I live just downstream 1km from the Carillon dam).

 

https://static1.squarespace.com/static/525bf175e4b00f431dc971c0/t/525ca7f6e4b048ac9edb6cb0/1381804022438/Geology+Of+The+Ottawa+Area.pdf

 

These sedimentary units are overlain by more fossiliferous shallow marine strata, beginning with the mixed sandstone-dolostone of the March Fm. and then dolostone-limestone of the Beauharnois and Carillon formations.

[Metawatch]

Digging deeper it looks like I struck paydirt here...https://curve.carleton.ca/system/files/etd/213f233e-58b8-401c-bfab-166d328727f7/etd_pdf/7b6190d5dc44cc42ebce77dbf41f4b13/alrodhan-tectonostratigraphyofthemiddleordoviciancarillon.pdf

 

I am going to take a guess it is Bioturbated Dolomudstone  from the Carillon region of the Middle Ordovician period from the attached reference document.

 

A further educated assessment would be appreciated by one who can comprehend the thesis above.

 

THanks again Don for setting me on the right path...

 

 

 

[Metawatch]

 Last but not least

 

https://www.nrcresearchpress.com/doi/pdf/10.1139/e06-030

 

The Carillon Formation

[Metawatch]

Thanks Kane. The weathering aspect is the one I hadn't even considered, and see that it has also shown up in mulitiple studies done in the area.