Saturday, July 25, 2009

Day 204: The Tablelands

Day 204: The Tablelands, originally uploaded by susanvg.

Today we hiked on the Tablelands. It was really fascinating. We had an excellent guide who explained the geology and the plant life. This site was one that helped geologists develop the theory of plate tectonics. This is one of only 5 places in the world where the mantle of the earth is visible and this is considered to be the most extensive site. 450 million years ago the ancient continents of Godwana and Laurentia came together forcing part of the floor bed of the Iapetus Ocean to rise. The mountains to the east of the Tablelands were formed from the earth's crust that had been on the ocean floor – they contain limestone and sandstone. The Tablelands were formed from the mantle deep within the ocean floor. It was thrust up to create mountains. When the continents again moved apart, Newfoundland was a hybrid. A section of the west (the Northern Peninsula) was once part of the ancient continent of Laurentia. A mountain range that was on Laurentia is now the Appalachians which go from the US up through part of Quebec, New Brunswick and Newfoundland. The Caledonian mountains in Scotland are part of the same range and continue in Scandinavia. The central part of Newfoundland was formed by volcanic rock which erupted when the old continents met and the third part of the Newfoundland, the Avalon Peninsula was part of what is now Africa – it was part of Gondwana.

The rocks – peridotite –are full of heavy metals which oxidize in the air so they have a rusty orange appearance. These metals are toxic to plant growth – few plants are able to survive near them. Those that have are quite stunted – junipers that live hundreds of years but hug the ground, tamaracks that do not grow much higher. Flowers that reach 60 centimeters in the garden grow to less than 10 in this hostile environment. There were some small flowers which can tolerate and use the metals. So the mountains are quite barren. There are the odd boulders which were carried by the glaciers and contain calcium and other minerals which plants feed off – they have lichen and algae on them. We saw some pitcher plants – the provincial flower of Newfoundland.

Across the road are mountains that support forests – they come from the earth's crust and so are more hospitable to life.

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1 comment:

  1. I'm amazed that you remembered all that information.