So You Want to Know About Rocks?

The rocks you see in the Creighton – Denare Beach – Flin Flon (CDF) region are a reflection of the earth’s changing geological and climatic environment over a 4.5 billion year history. Their contained riches are in fact what led to the founding of the communities in the CDF region. The oldest rocks in the region are precambrian in age, formed approximately 1.8 billion years ago. Fine-grained, greenish volcanic rocks were generated in an oceanic island environment similar to the present-day islands of Japan and Hawaii (and you thought it was hot here now!)  These are referred to as Amisk volcanics.

The copper-zinc base metal deposits currently mined in the region formed within these volcanic rocks at the same time. Molten rocks within the earth intruded the volcanic rocks and cooled below the earth’s surface, forming coarse-grained, gray and pink granite rocks.

As is happening today, plate tetonic processes were active during the time that the volcanic rocks were deposited.

During plate collision, the rocks were deformed into a continental mountain belt that extended from the Arctic to Wyoming, similar to the present day Rocky Mountain chain. Gold deposits in the area formed when gold-bearing fluids migrated through and in the fractured rocks, exposed as gold and quartz. River systems eroded these rocks over time, cutting deep into the earth’s surface to form sedimentary rocks. These recycled rocks, referred to as the Missi sediments, contain cobbles and castes of the older volcanic and granite rocks and are approximately 1.7 billion years old.

Renewed deformation caused the Missi sediments to also become folded and contorted. The rocks we see today represent the roots of this ancient eroded mountain belt.

During Ordovician time (450 million years ago) the area was covered by an ancient warm sea similar to the present day Caribbean. Coral reefs and lime muds were deposited on the ocean bottom and compacted to form limestone.

Remnants of this area are exposed as limestone cliffs along the south shore of Amisk Lake and 2 km north of Meridian Creek on Hwy. 167 at the abandoned fire tower station. In more recent geologic times, approximately 20,000 years ago, a 2 km thick sheet of ice of the Wisconsin glaciations blanketed the area. The present day topography of rolling hills and cliffs were sculpted by these ice sheets, which also deposited pockets of sand and gravel.

Present day ground and surface water erosion has continued to modify the earth’s surface. Its effect is most notable on the Ordovician limestone, where freeze-thaw action of the water and cautioning of the limestone has created crevasses and caverns for the modern day adventurers to enjoy.

Maybe that exotic island vacation isn't that far off after all; 1-2 billion years ago that is!