Stop 8 (1)
The rocks around Elliot Lake offer clues about the processes that shaped the Earth. Formed more than 2.5 billion years ago by volcanic activity, this very ancient land surface was shaped by massive earthquakes, periods of glaciation, plus extreme weathering, making this area famous the world over for the variety of rocks found here. Millions of years after these cataclysmic events, vegetation and animals appeared. In more recent times, pictographs discovered on rock faces have indicated that human beings were present in this area several hundred years ago, perhaps even longer.
I researched the geological history of this area, getting advice from Rob Henderson, a former geologist with Rio Algom. I also referenced an excellent guidebook,” Geology and Scenery, North Shore and Region”, written by Robertson & Card and published by the Ministry of Natural Resources.
· The top of the mural represents the Archean era , more than 2500 million years ago, when volcanic activity formed ancient volcanic and sedimentary rocks. Examples of Archean (known as Algoman granitic) rocks can be seen on the west side of Highway #108 along the power line after exiting Highway # 17.
· The next level depicts sedimentary rocks from 2200 to 2500 million years ago, known as the Keewatin banded iron formation (found very close to the airport, on the east side of Highway #108.
· The dark band of rocks is an intrusion of the Nippissing Diabase, formed about 2160 million years ago by further earthquake activity. These intrusions can be seen in many rock faces along Highway #108.
· A glacier formation, in the next band on the mural, represents several glacial periods in this region when rocks were moved and shaped by the force of the ice. Rivers deposited silt and sediment in other locations.
· The area below the glacier is the Mississagi Formation, which is the large rock face that can be seen across Horne Lake.
· From the Paleozoic Era (400-600 million years ago) there is a narrow band of rock containing fossils. Some evidence of fossils has been found around the Boland River area.
· Below the band of fossils, the Gowanda conglomerate is depicted. This type of rock was mined for Uranium.
· As vegetation followed the formation of the rocks, Birch trees are part of the strata. Birch trees are one of the oldest species of trees found world-wide.
· In the water below the trees are found representatives of Amphibians, Reptiles and Fish which first evolved in the water.
· Brick-red rocks, found just north of Elliot Lake (the Oompa Lake fault), serve as the backdrop for some of the animals & insects that have evolved in this area.
· The pictographs on the rock face at the bottom centre are from the Gowganda Formation, and are similar to some of the vestiges of ancient rock art found on Rooster Rock on Quirke Lake. According to the “Geology and Scenery of the North Shore”, human inhabitants were present in this region at least 9000 years ago.
Linda Finn 2014
For information about Linda and her work visit lindafinn.com