Maritimes

August 4 to 21, 2009

Aug 17: geocaching

Arisaig Earthcache was our first stop of the morning... and it turned out to be a great little spot.

Arisaig Provincial Park, overlooking the warm waters of the Northumberland Strait,
offers a fascinating window to life on Earth some 443 to 417 million years ago.

The rocks of Arisaig Provincial Park represent a continuous record of conditions in a shallow, storm-frequented sea from the Late Ordovician period (448 million years) through the entire Silurian to the Early Devonian (401 million years). They also highlight the differences between northern and southern Nova Scotia. The older rocks of southern Nova Scotia contain few fossils suggesting an environment that was inhospitable to most life forms. Arisaig is representative of northern Nova Scotia; fossils found in the rocks here show an abundance of life forms that suggest warmer waters, sunlight and an abundance of food. Between Early Silurian and Late Carboniferous time, Gondwana, North America and other continental plates collided to produce the mega-continent Pangea. When Pangea began breaking apart some 225 million years ago, the process left southern Nova Scotia attached to northern Nova Scotia. Most geologists consider southern Nova Scotia to be a fragment of Gondwana.

Precambrian volcanic rocks are found south of Hollow Fault, a major break in the earth’s crust. Arisaig Provincial Park is situated north of the fault on the younger Silurian rocks. The oldest rocks, dark and light coloured lava and pyroclastic flows, are found at Arisaig Point. The sedimentary rocks of the Arisaig Group, siltstones and sandstones (most with an abundance of fossils) begin at the Point and continue toward McAras Brook.