Nature Moncton Nature News: Nov 30 2021

NATURE MONCTON NATURE INFORMATION LINE, Nov 30, 2021 (Tuesday)

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Edited by: Nelson Poirier nelsonpoirier435@gmail.com

**Rosita Lanteigne came across a very large mushroom growing on a spruce tree on November 29, 2021 and submits a photo.

In consulting with Alfredo Justo and Amanda Bremner at the New Brunswick Museum, they have identified it as the Giant Panas (Lentinus levis). They comment only one specimen of this species is in the museum collection.

**While driving recently along the TransCanada Highway between Fredericton and Woodstock, the very interesting rock formations exposed when building the highway were eye-catching to look at more closely. With geologist savvy close to nil, I consulted for comments from Matt Stimson with the New Brunswick Museum.

Matt’s comments are too good not to share and hopefully will have other naturalists pausing to take a look and knowing a bit of the story behind these rock formations. Matt Stimson’s interesting comments are paraphrased below:

Paraphrasing Matt

Matt consulted with Dr. Adrian Park and the two of them agree that there are 2 different rock types here. The grey vertical rocks: these look like what are known as the Burtts Corner Formation. The Burtts Corner Formation is a grey sedimentary unit that was deposited underwater as what is known as a turbidite deposit. Turbidites are underwater landslides typically on the continental shelf which result in a graded sequence of coarse to fine sediments. The sequence of sedimentary structures is called a Bouma sequence, but I will not bore you with the finer details. Locally these shales contain fossils of Graptolites which are a colonial planktonic organism that live in marine, (salt water) seas and oceans. They are a very useful fossils as relative age date indicators. Based on the presence of certain species of graptolite, these rocks are late Silurian in age (430-425 million years ago).

for more information on the Burtts Corner Formation:

http://dnr-mrn.gnb.ca/Lexicon/Lexicon/Lexicon_View.aspx

Although at first (from his phone) Matt thought these may be sedimentary rocks, but upon using a larger screen and consultation with Dr. Park the lighter coloured rocks are indeed a granite known as the Pokiok Batholith. This is part of a larger suit of plutonic (magmaic) rocks in the area. The granite has been age dated to roughly 415 million years old to as young as 402 million years old based on uranium-lead radiometric age dating.

You'd asked about the water flowing through the rocks. Most rocks have some degree of porosity and permeability which water flows though like a sponge. Some rocks are less porous or less permeable than others. During the last glacial period, the Earth's crust was depressed into the Earth's mantle due to the weight of the overlaying glacial ice. As the glaciers retreated, the Earth's crust rebounded and began to rise back to its normal position in equilibrium with the underlying mantle rocks; a process called isostatic rebound. This is like holding a beach ball under water and letting it go, but much slower on geological time scales. This process cracks and fissures rocks. We call these parallel cracks "unloading joints". They add space for water to flow through the rocks more freely. What you have photographed is the Pokiok Granites that have been fractures as a result of the glacial retreat, "isostatic rebound” resulting in unloading joints in the rocks. Ground water is flowing though these cracks and fissures until it reaches the cliff face and open air, where the rocks and fissures are exposed at the earth surface due to the excavation. The water flows out and, in this case, has frozen into a beautiful waterfall.

for more information on the Poliok Granite:

http://dnr-mrn.gnb.ca/Lexicon/Lexicon/Lexicon_View.aspx

One could further consult with the NB Geological Survey who are the experts on these rocks as they deal with the bedrock geology of the province.

**The New Brunswick Environmental Network has published a schedule of events that will take place in December. The list of interesting topics is in the table below and space can be reserved to partake in these presentations by clicking on the event and registering.

The NBEN is proud to share information on upcoming events available to those interested in the environment. If you would like your event to appear in our monthly calendar email, please make sure to post it on our on-line calendar by logging into the Eco-Community and filling in the details here.