I have been doing field work at the estuary where the Folly and Debert Rivers meet and join the Minas Basin. My field work has focused on locating a historic limestone where Charles Lyell found marine fossils in August of 1842. This is a beautiful area of the Cliffs of Fundy UNESCO Global Geopark. Here, the meandering Folly and Debert Rivers flow into the biological diverse salt mashes and tidal estuary. The limestone unit where Lyell found his fossils is part of a small enigmatic outcrop of Carboniferous bedrock, otherwise surrounded by Triassic aged sandstone.
This field work has been exciting. It is thrilling to find a fossil site that Charles Lyell studied nearly two hundred years ago.
Geoheritage & Geodiversity
Over the past several months I have also been facilitating the Geoheritage Summer Institute. This is a collaborative learning project among a group of local academics and community members. The goals include building knowledge about geoheritage and building new collaborations between academics and communities to support sustainable development.
To establish understanding across a diverse audience, I introduced definitions and concepts of geoheritage after introducing the idea of heritage in general.
Heritage is our legacy from the past, what we live with and value today, and what we pass on to future generations.
World Heritage – UNESCO
Geoheritage, geological heritage, includes geological sites, landscapes, and material collections of significant scientific, educational, cultural, or aesthetic value.
Discussions of geoheritage also lead to reflecting on the important concept of geodiversity.
Geodiversity, geological diversity, has been defined as “the natural range (diversity) of geological (rocks, minerals, fossils), geomorphological (landforms, topography, physical processes), soil and hydrological features. It includes their assemblages, structures, systems and contributions to landscapes” (Gray, 2013, p. 12).
Nova Scotia is endowed with a rich geodiversity because of its historic location in the centre of the supercontinent Pangaea. The geomorphology was further shaped by the history of glaciation and abundance of coastal areas that expose the diverse bedrock.
Geodiversity of the Debert River
My efforts of retracing the steps of Charles Lyell along the Debert River, is an example of geoheritage. This fossil site played an important role in the history of geology. Relocating the site has brought to light other interesting cultural history and appreciation for the beauty of this tidal estuary. This field work also has me thinking about the river’s geodiversity. The water flowing down the Debert River travels across rocks representing six hundred million years of geological history.
The Debert River’s source begins at Debert Lake, in the Cobequid Highlands. The rocks surrounding Debert Lake are composed of Devonian/Carboniferous Byers Brook Formation. As the water moves downstream it passes over rocks further back in geological time. The water passes over 400 million year old granite and then 600 million year old rocks of the Gamble Brook Formation. Continuing to flow, it reverses course in geological time, moving over younger rocks from the Carboniferous and even younger Triassic aged rocks. The water then passes over the small outcrop of limestone where Charles Lyell found his fossils in 1842. It is in this estuary that the water of the river joins the Minas Basin to become part of the world’s highest tidal range.
- Devonian/Carboniferous – Byers Brook Formation
- Devonian/Carboniferous – Granite
- Devonian/Carboniferous – Diamond Brook Formation
- Neoproterozoic – Folly River Formation
- Cyrogenian/Neoproterozoic – Gamble Brook Formation
- Late Carboniferous – Mabou Group
- Late Carboniferous – Pictou Group
- Late Triassic – Wolfville Formation
- Early Carboniferous – Tennycape and Pembroke Formation
- Late Triassic – Wolfville Formation
- Modern Minas Basin, highest tides
The water flowing down the Debert River travels 33 km, from an elevation of 263m down to sea level. The geodiversity the water is exposed to during its journey is an important aspect of this heritage river. The geodiversity affects the morphology of the river and biodiversity found in its waters and along its banks.
Geological map with Debert River with elevation profile from Google Earth. Within the terrain under-laid by the Triassic Wolfville Formation (light brown), an 11,000 year old Mi’kmaw site is located one kilometer from the river’s edge.
The most significant heritage site along the Debert River is the archaeological discovery made one kilometer from the river. A diverse assemblage of Mi’kmaw tools and points of agate were excavated in 1960s, and dated at over 11,000 years old. These artifacts were made of agate sourced from the North Mountain Basalt, from sites further to the west and outside of the Debert River watershed.
The Debert River has flowed for thousands of years, across a diverse geological landscape. On August 10, 1842, Charles Lyell stood here and pondered the age of marine shells found in limestone. Today, it is through geological methods and knowledge that we can appreciate the importance of the geoheritage and geodiversity of this river.
Mi’kmaw Story Sites
Learn more about Mi’kmaw story sites and geology of Nova Scotia from this presentation by Gerald Gloade.
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