Some may say that PEI is geologically boring, but I think nothing could be further from the truth! Our sandstone bedrock holds fascinating stories about the time in which it was formed, some 300 million years ago. Last week we looked at what it tells us about ancient monsoons and lakeshores. This week, we learn what it has to say about the prehistoric forests that grew here during the late Carboniferous and early Permian Periods.
At this time – about 60 million years before dinosaurs – the land that was to become Prince Edward Island was in the centre of the supercontinent Pangea and located near the equator. The climate was hot and dry for part of the year, before seasonal flooding returned. This was a change from the hotter, consistently wet and swampy conditions of the earlier Carboniferous Period (aka Coal Age) and PEI’s plant fossils record this transition.
Calamites (Photo 1) was a tree of the Carboniferous Period and an ancestor of today’s Horsetail plants (Equisetum spp). Growing to heights of 10 to 12 metres (30 to 40 feet), Calamites was able to reproduce both reproductively by spores and vegetatively by rhizomes, and so would have formed dense stands in the understories of Coal Age swamp forests. Like its much smaller modern-day relative, Calamites had hollow, segmented stems and branches which make its fossils fairly easy to identify. They’re relatively common around PEI’s coast.
Lepidodendron (Photo 2) is an ancestor of today’s Quillworts (Isoetes spp.) and Clubmosses (Lycopodiaceae Family). Also part of the Coal Age flora, it towered over the landscape with heights of up to 50 metres (160 feet) and diameters as much as two metres (6.5 feet) at the base. Many of the large stumps at the famous Joggins Fossil Cliffs in Nova Scotia are Lepidodendron, and they are common in a few areas along the south shore of PEI. The diamond-shaped pattern from its thick bark makes Lepidodendron fossils distinctive.
Another swamp-loving Carboniferous species was the tree-fern Pecopteris (Photo 3), growing to heights of 15 metres (about 50 feet) and diameters of about 1.5 metres (five feet). The cooling, drying climate during the Permian didn’t suit this species and – though it had existed since the Devonian, more than 100 million years earlier – it wasn’t able adapt. Pecopteris disappeared during the Permian, but its fossils are common in Western PEI, and it’s one of my favourites to find.
The Permian climate was well suited for early conifers, such as Walchia (Photo 4) which would have resembled today’s Norfolk Pine (Araucaria heterophylla, often used as a houseplant). This tree was about 12 metres (40 feet) tall and a dominant species of the Permian landscape. There’s a world-class forest of Walchia stumps across the Strait in Brule, Nova Scotia, and Walchia fossils are commonly found along PEI’s shores as well.
Taken together, the information about prehistoric land and plants paints a picture of what our part of the world may have looked like 300 million years ago (artist’s depiction, Photo 5). Fossils are important records that help scientists understand how life on Earth evolved. If you find one on PEI, take photos, record the location, and contact archaeology@gov.pe.ca or Laura MacNeil at Prehistoric Island Tours. Fossils are protected in this province and it’s not legal to collect them without authorization.
PEI is rich in plant fossils, and globally-significant animal fossils and trackways have been discovered here as well. If you’re interested in learning more, join me on 18 February 18 2025 when Laura MacNeil will be the special guest at my monthly Zoom workshop. She’ll guide us through PEI’s geology and recent fossil discoveries that are re-writing what we know about the Permian Period. You can find all the details here: https://www.pei-untamed.com/event-details-registration/introduction-to-pei-geology-and-fossils
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