Horizon

Vista of hazy hills in Tuscany

These photographs of the hazy horizons of successive hilltops in the Tuscan countryside are views looking southwards from the top of Brunelleschi’s dome on the cathedral of Santa Maria del Fiori, the Florence Duomo. Spectacular vistas of the city and its surrounding countryside are the reward for climbing 463 steep steps in claustrophobic narrow passageways of herringbone brickwork through the interior of the dome.

Vista of hazy hills in Tuscany

Vista of hazy hills in Tuscany

Rock Texture & Pattern at Black Brook Cove

Patterns of dykes in granite in the cliffs at Black Brook Cove

Black Brook Cove along the Cabot Trail in Cape Breton Island, Nova Scotia, gets its name from the dark colour of the river water which flows into it. On the southern edge of the cove, the upper banks of the estuary are piled high with large bleached driftwood lying on a bed of boulders and pebbles. Curving banks of pebbles on the main body of the beach give way to smooth waterworn rock outcrops; and spectacular jagged cliffs surmounted by pines form the northern arm of the cove.

The rocks at Black Brook Cove are part of the Devonian Black Brook Granitic Suite formed about 375 million years ago. They are igneous plutonic rocks. The magma from which they formed was created by the melting and recrystallization of meta-sedimentary rocks that were sub-ducted during the collision of the ancient land masses called Ganderia and Avalonia.

The remarkable feature of the rocky outcrops at Black Brook Cove, and at Green Cove just a little further south, is the number of criss-crossing dykes or veins of contrasting colour that create abstract angular patterns on the rock surfaces. These patterns and colours are accentuated when the rock is wet. The whole beachscape is captivating on a bright sunny afternoon but the area must look its best after a heavy downpour of rain.

The main rock is a grey granite with small black flakes of biotite. Earth movements and increased pressures on numerous occasions subsequent to its emplacement have cracked the rock and opened up fissures into which certain minerals that were squeezed out of the mother rock have entered and recrystallized. Mostly the veins formed in this way are composed of aplite or pegmatite. Both are pink-orange in colour Aplite is made of quartz and feldspar and is fine-grained with a smooth sugary texture. Pegmatite is darker and coarser with large visible individual crystals of quartz, feldspar and mica in both the black biotite and clear muscovite forms.

REFERENCES

Anoiyothin, W.Y. and Barr, S.M. (1991) Petrology of the Black Brook Granitic Suite, Cape Breton Island, Nova Scotia. Canadian Minerologist, Vol. 29, pp. 499-515.

Barr, S.M. and Pride, C.R. (1986) Petrogenesis of two contrasting Devonian Granitic Plutons, Cape Breton Island, Nova Scotia. Canadian Minerologist, Vol.. 24, pp. 137-146.

Donohoe, H. V. Jnr, White, C. E., Raeside, R. P. and Fisher, B. E, (2005) Geological Highway Map of Nova Scotia, Third Edition. Atlantic Geoscience Society Special Publication #1.

Hickman Hild, M. and Barr, S. M. (2015) Geology of Nova Scotia, A Field Guide, Touring through time at 48 scenic sites, Boulder Publications, Portugal Cove-St. Philip’s, Newfoundland and Labrador. ISBN 978-1-927099-43-8, pp. 94-97.

Atlantic Geoscience Society (2001) The Last Billion Years – A Geological History of the Maritime Provinces of Canada, Atlantic Geoscience Society Special Publication No. 15, Nimbus Publishing, ISBN 1-55109-351-0.

St Ann’s Provincial Park

St Ann’s Provincial Park along the Cabot Trail in Cape Breton Island, Nova Scotia, Canada, was just springing into life after a cold winter when we visited earlier this year. It was a brief stop for a picnic lunch on our way from the Cape Breton Highlands National Park to the Louisbourg area on the east coast. The park  lies on the northern shore of the stretch of water known as North Gut, and has a short trail leading to a look-off where there are views over the saltmarsh and St Ann’s Bay. We did not have time to venture very far down the trail but, even by the car park, there was plenty to enjoy.

Bright green ferns of various types were uncurling their fronds. The compacted fern buds are called fiddleheads. Particular varieties in some localities are a feature on menus at this time of the year (we tried some and they were delicious). Golden mosses covered the ground, while bladed marsh plants were breaking through the winter’s debris on the water margin. Delicate white blossoms quivered on trees of the woodland edge. The greatest delight was catching sight of a snake making its way through the leaf litter. I am not certain what sort but it might possibly be a Maritime Garter Snake.

Rocks at Wasson Bluff

Wasson Bluff is famous. A site with an international reputation. It is located to the east of Parrsboro on the northern shore of the Minas Basin in Nova Scotia, Canada, and is best known for its fossils and its fascinating geology. Canada’s oldest dinosaur skeletons are being excavated in earliest Jurassic sedimentary rocks at Wasson Bluff Palaeontological Protected Site. Within these rocks an important vertebrate fauna including jaw bones and skulls of a rare protomammal, Pachygenelus were discovered, and also bones and scales of the lizard-like reptile Clevosaurus, a crocodile-like reptile Protosuchus, fish scales and prosauropod dinosaurs (Donohoe et al. 2005).

The bluff consists of complexly faulted and tilted sedimentary rocks and basalt. Most of the rocks of the Bluff itself are composed of brownish Jurassic North Mountain Basalt with evidence of hexagonal cooling joints. Much of it is brecciated. The basalt boulders that have fallen to the beach include many with pockets and streaks of various minerals; the green deposits seen in the photographs of boulders on the beach may be the mineral celadonite. A fault brings the mostly brecciated basalt into contact with The Triassic Partridge Island Member of the Upper Blomidon Formation. The Blomidon Formation rock is described as well-bedded grey, red and purple sandstone and mudstone with the Partridge Island Member of it being conglomeritic but fining upwards to siltstone but beneath the basalt. This junction of rock types can be seen in images 1 and 17 in the gallery of photographs above this text and image 25 in the gallery below.

Carboniferous Parrsboro Formation “red bed” strata are exposed for a short distance to the east of the bluff and on the east of the small stream that traverses a narrow, steep sided, tree-lined valley before it crosses the beach.

Further east along the beach, the soft red Jurassic period McCoy Brook Formation rocks which originated as sediments associated with rivers, lakes, and wind-blown sand dunes form a low crumbling cliff and can be seen in the photographs as the brighter red rocks often with white stripes and patches.

The local Fundy Geological Museum conducts tours of the site and works with academics on fossil excavations at the site every summer.

Please note that all the identifications attached to the photographs of the rocks are tentative and subject to verification – I am just an interested natural historian and not a professional geologist.

REFERENCES

Donohoe, H.V.Jr., White, C.E., Raeside. R.P., and Fisher, B.E. 2005. Geological Highway Map of Nova Scotia, Third Edition. Atlantic Geoscience Society Special Publications #1.

Nova Scotia Field Guide, Arthur D. Storke Memorial Expedition, Department of Earth and Environmental Sciences, Columbia University in the State of New York, August 23 to September 2, 2012.

Parrsboro Shore

Beachscape with lighthouse at Parrsboro, Nova Scotia, Canada.

Views of the Parrsboro shore and harbour at low tide one evening in May 2016. We stopped off there to have a seafood supper at the Harbour View Restaurant. The tidal rise and fall on this beach can be as much as 45 feet and the sea goes way out. Boats moored in the harbour are stranded on the mud at low tide. The small town of Parrsboro lying a little further inland and up river of the shore is where we based ourselves to explore the area. We stayed at the Parrsboro Mansion Inn from which we travelled out to Joggins Fossil Cliffs, Cap D’Or, Spencer’s Island, Clarke Head, and Wasson Bluff. On a previous visit to the area in 2014 we visited the Fundy Geological Museum, Partridge Island, and Joggins.

Beachscape with moored boat at Parrsboro, Nova Scotia, Canada.

Beachscape with lighthouse at Parrsboro, Nova Scotia, Canada.

Beachscape with red cliffs at Parrsboro, Nova Scotia, Canada.

Beachscape with evening light reflected on mud at Parrsboro, Nova Scotia, Canada.

Beachscape with lighthouse at Parrsboro, Nova Scotia, Canada.

Beachscape with low tide standing water pools at Parrsboro, Nova Scotia, Canada.

Pea Stacks from Moulin Huet Bay

Silhouetted rocky outcrops of the Pea Stacks in Guernsey

The view seawards from Moulin Huet Bay in Guernsey has been immortalised on many an artist’s canvass, including Pierre Auguste Renoir whose work is highlighted by a sign at the bay itself. He painted the scene fifteen times during a month long stay in 1883. The jagged outcrops that feature in the picture are the Pea Stacks (which are sea stacks) carved by wave action into the Pea Stack Gneiss rock on the very tip of the Jerbourg Peninsula. This metamorphic rock differs in appearance and origin from the Icart Gneiss of Moulin Huet Bay and the Doyle Gneiss that makes up the main part of the peninsula.