18 June 2013 Green Point Geology

Today, Tuesday, Patrice got her hair cut at a nearby beauty salon, I arranged to have an empty propane tank filled (very expensive propane here), and we had breakfast downtown. I had some moose sausage and eggs, and Patrice had a crab omelet--that's crab with a "c" not a "k."

Then Patrice and I visited Norris Point, the Lobster Head Cove Lighthouse, the SS Ethie ship wreck, and Green Point, all discussed in yesterday's posting of this blog. Geology holds an interest for both Patrice and me, and we spent about three hours at Green Point. With the field guide "Geology of Newfoundland" and our cameras at hand, we explored Green Point to understand why it is so important to the study of the world's geologic history. This was an exciting excursion.

In order to get to the boundary layer, we walked on the shale and limestone slabs and layers--like crumbly pages underfoot. They were so regular, and some of them were worn so smooth that they looked like the grain lines in wood. Lichens and mosses covered some of the upper shore, and seaweed and barnacles covered the tidal rocks and layers. There are fossils galore, found between the layers; however, fossil gathering is strictly prohibited.

Our visit at low tide today allowed us climb around the barrier at the right, which the high tide obstructed yesterday. We were able to reach the boundary layer (known as Bed 23) where the steeply tilted beds of shale and limestone of the Cambrian Period lie directly below those of the Ordovician Period. The importance of this location is that nowhere else in the world is this boundary so clearly designated. [Note: The Cambrian Period occurred between about 545 and 490 million years ago and the Ordovician Period occurred between about 490 and 440 million years ago.]

Cambrian/Ordovician Boundary Layer at Green Point

Note that boundary layer directly below two rocks at surface

Cambrian/Ordovician Boundary Layer

The fossil types of the Cambrian Period (trilobites) and of the Ordovician Period (shellfish and fish) were used to define this boundary layer. Because the definition of this boundary was so complete and well preserved, the International Union of Geological Sciences designated, in January 2000, Green Point in Gros Morne National Park as a Global Stratotype Section and Point (GSSP).

Tilting of the sediment layers (shale and limestone) seen at the Green Point site were caused by plate tectonics, i.e., the movement of large rock plates. The process of plate tectonics helped create Newfoundland; that's another story to be continued in later blogs.

Tomorrow we all go on a two-hour boat tour of Western Brook Pond. That's another exciting excursion!

There are no lakes in Newfoundland, only ponds.