Maritime Beaches: Their Grim Story
One might suppose, judging by this title, that the beaches in Canada’s maritime provinces are not happy places to visit. Actually they are beautiful. Nevertheless, the story of these landscapes provides remarkable food for thought.
Our journey starts just inside the province of Quebec, on the southern coast of the Gaspe Peninsula. Follow the signs from the town of Nouvelle, to the museum in Parc national de Miguasha. A small but completely bilingual museum overlooks the beach. The cliff behind the building is still actively excavated for fossils, and palaeontologists daily walk along the shore to look for fossils freshly eroded from the cliff. Visitors to the museum do not take long to discover that fossils from these cliffs tell a fascinating tale of horror and destruction.
This beach has long been famous for the exquisite nature of the fish fossils found there. Dramatic evidence of the fate of the Miguasha fishes is apparent throughout the entire 118 m depth of rocks which preserves this watery community. The same species are found throughout this entire rock deposit. This strongly suggests that no lengthy time interval separated the fish entombed at the top and bottom of the deposit. Even modern lakes and oceans may show changes in species composition over time, but this community does not show this. Thus whatever happened, it happened quickly.
It appears that rivers of sand and clay, in pulse after pulse, were swept by watery torrents from nearby hills, down upon the fishy community in the depths. Carried along with the sediments came fragments of giant fern trees (Archaeopteris Archaeopteris) and some horrible scorpion-like creatures. The sediments separated as they settled into characteristic patterns of coarser and finer layers. Such patterns are considered to be an indication of the rapid deposition of these sediments. These under-water avalanches are called turbidity currents and specialists easily identify them. Indeed, all the sediments that were laid down in this body of water, were turbidites.
The fish themselves, trapped in these sediments, bear ample testimony to the sudden nature of the disaster which overtook them. In some cases soft internal tissue, as well as hard bones and scales are preserved. Also the hard parts of entire fish are often found. All this indicates a very rapid burial, before rot or scavengers could take their toll, causing disintegration of the skeleton. Even more interesting are fish preserved in the postures of life: for example, a lungfish dining on crustaceans; a ray fin fish cannibalisitically eating a smaller specimen, head first. Death and burial came to these fish as they pursued their normal activities. Indeed, many specimens of armoured fish and also lungfish have been found in the posture of swimming, apparently oriented by brisk water currents advancing from the northwest. All such fish were advancing into the current.
Another indication of sudden burial are the fish specimens with exploded guts. The abdominal cavities are open at the front with scales scattered nearby in the sediments. It seems that gas generated in these decaying bodies, could not escape because the carcasses were entombed. Finally the abdominal wall gave way and the gas eventually dispersed into the sediments.
Faced with these astonishing artifacts, geologists have come to the obvious conclusion that these fish were buried rapidly. Most experts however assume that pulses of crisis interrupted long periods of normalcy. This is not however a reasonable conclusion. The fact that the whole rock column is so similar, suggests that this was a one time event, a flood of astounding proportions – no doubt a worldwide event.
Leaving Miguasha, we cross New Brunswick and come to Amherst, Nova Scotia. We continue on the main highway towards Halifax, but turn west at Truro. This takes us to Hantsport. We are now on the south shore of the Minas Basin, part of the Bay of Fundy. The incredibly high tides of the Minas Basin (14 m), have served to expose fossil beaches at nearby Horton Bluff and Blue Beach. The ripple marks look fresh, but are actually rock (said by experts to be 350 million years old – 20 million years younger than the Miguasha rocks). These fossil beaches also preserve footprints made in the sediments. At Horton Bluff, some footprints are so large (each about 30 cm long) that experts now tentatively identify the animal as a semiaquatic predator called Eryops. This extinct amphibian grew to over 2 m long. The first observation of such footprints was made by Sir William Logan, first director of the Geological Survey of Canada. Other experts of the time (19th century) however ignored Sir William’s report because they did not believe any four footed animals existed in that long ago time, certainly not such huge ones.
Nearby at Blue Beach, a wide array of tracks is preserved in sandstone, everything from fingernail size footprints to Eryops size. The temporary nature of these traces made in wet sediments, suggests that each layer was buried by the sudden arrival of further waterborne sediments. The absence of bones suggests that the creatures themselves may have been swept away in the same catastrophic event.
We next take the ferry from North Sydney (on Cape Breton Island), to Newfoundland. Once there, we follow highway #1 as it heads north east, and soon turn west to Stephenville, on a tiny cape in the Gulf of St. Lawrence. Here, in a river valley north of the town, we find a collection of fossil tree trunks, stumps with attached root balls, and branches of what were once gigantic coniferous trees.
These extinct cordaitalean trees grew here up to 48 m tall. Geologists who work the site conclude that these trees must have been shallowly rooted since the remains were washed from an upland plain, and dropped into a nearby valley. None of the roots (from stumps as long as 7 m) bears any traces of the original soil. This is a most interesting situation. The flooding must have involved extremely energetic water which was able to uproot gigantic trees, wash them free of debris, and bury them in rocks and gravel some distance away. This sounds like a very remarkable flood! The coarse sediments, with contained trees, lie on rock estimated by these experts to be more than 500 million years old. It is enough to cause one to wonder how reliable these time estimates (guesstimates?) really are. Did the flood really happen 300 million years ago, as the experts suppose? They confide that they dated the flood deposit based on the identity of the contained fossils. Is anything as old as they imagine?
Next issue we will continue our journey with visits to Joggins, Brule and Parrsboro, all in Nova Scotia. They are every bit as exciting. Why not plan your next vacation in Canada’s maritime provinces? Meanwhile it is good to remember that the offi cial interpretation of geological artifacts is not necessarily the correct one.
- Atlantic Geoscience Society. 2001. The Last Billion Years: a Geological History of the Maritime Provinces of Canada. Nimbus Publishing. Halifax. 212 pages.
- Howard J. Falcon- Lang and Arden R. Bashforth. 2004. Pennsylvanian uplands were forested by giant cordaitalean trees. Geology 32 #5: 417-420.
- H.-P. Schultze and R. Cloutier (editors). 1996. Devonian Fishes and Plants of Miguasha, Quebec, Canada. Verlag Dr. Friedrich Pfeil. Munich. 374 pages.
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