Newfoundland was eventually formed by the collision of tectonic plates 350-400 million years ago. (Click here for an interactive animation showing the motions of the continents over time.) This is when the Appalachian mountain chain was formed and when the limestone sea floor was lifted above sea level and eventually became the barrens. The limestone was submerged again about 10,000 years ago by the tremendous weight of 1-3 km thick glaciers covering Newfoundland during the ice age. It re-emerged after the retreat of the glaciers and glacial rebound is still ongoing. Glacial rebound is when a glacier moves away from an area and the tectonic plate which was previously weighed down into the mantle by the glaciers begins to float back to the top. This process is still ongoing in Newfoundland and can be illustrated by the dropping sea levels around the island.
Thrombolites are a unique geological feature of the limestone barrens. These thrombolites occur in the Flower's Cove area and they are the ancient growth structures of millions of tiny algae and bacteria. They have a clotted structure which was created when the bacteria precipitated calcium carbonate from the water as they photosynthesized. They are believed to have thrived in the tidal and sub tidal zone of a warm, very salty sea, some being exposed at low tide and covered at high tide.
Thrombolite at Flowers Cove
Frost sorting is a common geological anomaly on the limestone barrens. When water seeps into the cracks in limestone gravel and freezes, it starts to sort the gravel. The larger pieces are sorted from the smaller pieces. This process continues year after year, frost after frost, until a frost polygon or stone stripes eventually form. Frost polygons are circles of gravel with the larger pieces sorted to the outside, forming a ring, and the smaller pieces on the inside. They are often mistaken for human-made structures such as tent rings and crop circles, however they are natural. Stone stripes form in a similar way, except they form stripes of larger rocks and stripes of smaller rocks. This is usually because they form on the side of a hill or incline. Frost sorting can take decades, if not centuries, to form these geological feature.
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Limestone is often drastically affected by the chemical process known as carbonation. Water vapor readily dissolves carbon dioxide in the atmosphere and so the rain which falls contains carbonic acid. Carbonic acid dissolves limestone with large amounts of calcium carbonate in it. This can create underground streams and caves which can collapse causing sink holes. This makes for an unusually bumpy and pitted landscape. Erosion also makes for interesting coastal features including sea caves, sea stacks, terraces and so forth.
