Wasson Bluff (also known as Wasson's Bluff) is the name applied to a series of imposing cliff faces on the north shore of the
Minas Basin
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, caption = Looking east across the Southern Bight of Minas Basin from The Lookoff
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about east of the town of
Parrsboro
Parrsboro is a community located in Cumberland County, Nova Scotia, Canada.
A regional service centre for southern Cumberland County, the community is also known for its port on the Minas Basin, the Ship's Company Theatre productions, and t ...
,
Nova Scotia
Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland".
Most of the population are native Eng ...
.
[Thurston, Harry (1994) ''Dawning of the Dinosaurs: The Story of Canada's Oldest Dinosaurs''. Halifax: Nimbus Publishing and The Nova Scotia Museum.] The cliffs, which stretch approximately from Wasson Brook in the east, to Swan Creek in the west, consist of 200-million-year-old rocks that have yielded a wide array of
fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
s including more than 100,000 bones from Canada's oldest-known
dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
s as well as the smallest
dinosaur tracks
A trace fossil, also known as an ichnofossil (; from el, ἴχνος ''ikhnos'' "trace, track"), is a fossil record of biological activity but not the preserved remains of the plant or animal itself. Trace fossils contrast with body fossils ...
ever found.
[Lessem, Don (1992) ''Kings of Creation: How a New Breed of Scientists is Revolutionizing Our Understanding of Dinosaurs''. New York: Simon and Schuster.][Atlantic Geoscience Society (2001)''The Last Billion Years: A Geological History of the Maritime Provinces of Canada''. Halifax: Nimbus Publishing.] The fossils date from a critical time in the evolution of life, the boundary between the
Triassic
The Triassic ( ) is a geologic period and system (stratigraphy), system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Year#Abbreviations yr and ya, Mya), to the beginning of the Jurassic Period 201.36 ...
and
Jurassic
The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...
geological periods, when
mass extinctions
An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. It ...
led not only to the dominance of the dinosaurs, but also to the evolution of groups of
vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with c ...
s, such as fish,
crocodiles,
frog
A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-frog" ''Triadobatrachus'' is ...
s and
mammals, whose descendants are still alive today.
The abrasive action of the tides, considered to be the world's highest, constantly exposes fossils on the cliff faces, shores and seabed.
[Thurston, Harry (1990) ''Tidal Life: A Natural History of the Bay of Fundy''. Camden East, Ontario: Camden House Publishing.]
In 1990,
Paul E. Olsen, one of the
paleontologists
Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of foss ...
who has conducted extensive fossil excavations at Wasson Bluff wrote: "Every time I stand before these cliffs, I feel dwarfed by the immensity of time."
Geology
The cliffs at Wasson Bluff stand at the edge of the ancient
rift
In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics.
Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-grabe ...
valley known as the
Fundy Basin
The Fundy Basin is a sediment-filled rift basin on the Atlantic coast of southeastern Canada. It contains three sub-basins; the Fundy sub-basin, the Minas Basin and the Chignecto Basin. These arms meet at the Bay of Fundy, which is contained wi ...
. It was created when the
supercontinent
In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", which leav ...
Pangaea
Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million y ...
began to break up about 225 million years ago. As the
continental plates moved apart, they ruptured, and blocks subsided or rose along
fault lines
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...
creating complex, twisted layers of rock turned at odd angles.
[Roland, Albert E. (1982)''Geological Background and Physiography of Nova Scotia''. Halifax: The Nova Scotian Institute of Science.]
The orange and red
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicates ...
s visible at Wasson Bluff formed as rivers swollen by intense rains carried coarse sediments from nearby highlands into the Fundy Basin. Other deposits came from wind-blown sand
dunes or from the sediments on the bottoms of shallow lakes that, at various times, occupied the floor of the basin. As Pangea broke apart,
magma
Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...
rose to the surface through deep fissures in the Earth's crust erupting as
lava
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...
flows. This massive
volcanic activity
Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the surface called a ...
created the greenish-grey columns and grey-black blocks of
basalt
Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...
that form large sections of the cliffs.
Fossil discoveries
Tiny dinosaur tracks
On April 10, 1984, veteran fossil hunter and
amateur geologist,
Eldon George, made a discovery that drew the world's attention to Wasson Bluff. George was riding along the shoreline on his
all-terrain vehicle
An all-terrain vehicle (ATV), also known as a light utility vehicle (LUV), a quad bike, or simply a quad, as defined by the American National Standards Institute (ANSI); is a vehicle that travels on low-pressure tires, with a seat that is stra ...
when he stopped behind an outcropping to take shelter from the wind. As he bent over his ATV to warm his hands, his experienced eye picked out what appeared to be tiny tracks. Using a jackknife, he gradually exposed five fossil trackways imprinted in a slab of sandstone measuring . The three-toed, penny-sized footprints were made by a
theropod
Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...
dinosaur about the size of a robin. They were the smallest dinosaur tracks ever found.
Although the tiny dinosaur tracks are Eldon George's most famous discovery, he made many others in a career that began in the 1940s and ended with his death in 2018. His finds include a wide variety of fossilized
amphibian and
dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
prints that were displayed, along with the world's smallest dinosaur tracks, at his Parrsboro Rock and Mineral Shop before he donated them to a local geological museum in 2015. One of them, also found at Wasson Bluff, is a track that may have been made by a primitive, two-legged, crocodile-like creature that was nearly long.
Rich fossil beds
In January 1986, American paleontologists Paul Olsen and
Neil Shubin
Neil Shubin (born December 22, 1960) is an American paleontologist, evolutionary biologist and popular science writer. He is the Robert R. Bensley Professor of Organismal Biology and Anatomy, Associate Dean of Organismal Biology and Anatomy and ...
announced they had recovered hundreds of thousands of bones at Wasson Bluff, the largest fossil find in North America dating from the geological period 200 million years ago known as the Triassic-Jurassic boundary.
It was a time when massive lakes of lava spewed from fissures in the earth as the supercontinent Pangea broke apart. Some scientists believe that the volcanic eruptions and the poisonous gases they released caused
the mass extinction of nearly half of the world's creatures ending a period dominated by huge reptiles and enabling dinosaurs to become dominant. The sandstone and basalt cliffs at Wasson Bluff were formed during the Triassic-Jurassic boundary. They contain fossil remains of the creatures who lived both before and after the mass extinction.
In 1984, Neil Shubin found the jaw of a mammal-like reptile known as a
trithelodont, the first such discovery in North America. The next summer he and Paul Olsen, along with
Hans-Dieter Sues of the
Royal Ontario Museum and William Amaral, Charles Schaff, and Steven Orzack of Harvard University, uncovered 12 complete skulls of trithelodonts, a discovery that has helped scientists gain a better understanding of the origins of mammals. They also retrieved many other fossils including teeth from small,
bird-hipped dinosaurs, skulls of lizard-like creatures known as sphenodontids, ancestral crocodile bones and skulls, as well as fossilized fish and shark bones.
Restrictions on fossil collection
A special permit is required before anyone can collect fossils or use rock hammers in the Wasson Bluff area. The site is protected under Nova Scotia's
Special Places Protection Act. The law aims to preserve places that are important for cultural, historical and environmental reasons and that are significant sites for scientific research.
References
{{Reflist
External links
The Mineralogy of Nova ScotiaThe Fossil ForumPhotographic tour of Wasson Bluff
Landforms of Cumberland County, Nova Scotia
Tourist attractions in Cumberland County, Nova Scotia
Geology of Nova Scotia
Landforms of Nova Scotia
Cliffs of Canada