The limestone is nearly flat lying. This exposure is exceptional not just because of its large expanse and polish, but because it shows more than one ice direction. There are three directions of ice flow indicated by striations and grooves; they are approximately south, west and northwest, and were created in that order. The earliest of these is the dominant one.
There are also features called "sichelwannen": curved erosion structures with horns extending down-flow. In most cases at this locality, one horn is better developed than the other. While striations and grooves are caused by stones carried in the ice as it moved over the rock surface, sichelwannen are made by water flowing between the limestone surface and the glacier; because of the weight of the ice, the water pressure was extremely high. The entire surface is so fresh that it is believed to have been covered by sediments until very recently.
The limestone itself is Cambrian. It contains little balls of fossil algae, and other kinds of fossils can also be found.
To reach the quarry, take the gravel road to Three Mile Pond Provincial Park, located 8.8 km south of the junction of Routes 430 and 432 (to Roddickton). Drive along the gravel road for 1.9 km to arrive at the quarry on the left hand side. The farthest section of the quarry is being worked some of the time, but it has the best samples of fossil-bearing material. Warning! Falling rocks. Stay away from the cliffs. There is plenty of collecting material on the quarry floor. The shale is extremely friable if it has been exposed for any length of time, and the trilobites are found on the bedding planes, where they have a delicate bronze lustre. Specimens of Olenellus at this location are up to 3 cm across.
The high cliffs to the left of the active quarry area, above an older quarry, contain fossil limestone reefs, which were formed on top of the shales. The reefs appear as irregular bulbous masses in the cliffs.
The sequence here is believed to show the history of a muddy offshore region that gradually became shallower and cleaner as the sea level dropped. The organisms that built the reefs flourished in the cleaner environment.
A similar formation containing the same fossils is found in northwest Scotland, giving support to the theory that Scotland and Newfoundland were joined in Cambrian time as parts of the continent of Laurentia (see Plate Tectonics panel). Millions of years later, during the Mesozoic, they were broken apart by the opening of the Atlantic Ocean.
Drive into Englee, but do not cross the bridge. Instead, take the shore road to the left as far as possible and park. Walk past the last house and continue on the path around the point.
Before you pass the last house there is a power pole on the left with a large outcrop beside it that gives a clear look at the Ordovician rocks just underneath the thrust fault. Thin bedded, dark grey schist overlies paler grey marble. Sandstone beds have been stretched and broken up and the marble has been flattened out, although some parts still show the grey massive nature of the original limestone, streaked with white bands.
As you walk out and around the point, you will see more examples of deformed rocks. The quartz-rich layers, being harder than the shale, tend to weather higher, resulting in fantastic ridges. There is also microfolding, particularly of the shale, where layers were contorted on a tiny scale by the thrust movement.
Looking east across the cove, you can see a high ridge. This consists of metamorphosed, massive, Late Proterozoic sandstone of the allochthon.
At the farthest easy walking point, where the shore becomes a steep cliff, if you look
up, you will see that the shale has been intruded by a large, dark green diabase dyke. Some
pieces of the dyke have broken off and fallen onto the beach.
The marble here is extremely bright and white in sun, and erosion has emphasized the contorted folding. Some areas are pale grey, mottled white and shot through with white calcite veins. Marble is limestone that has recrystallized during metamorphism into this harder form; original bedding has mostly been obliterated, and folding and flowage have commonly taken place.
West of the marble exposure is dark grey metamorphosed shale, which forms the cliffs on this side of Canada Bay. Close to the contact it is highly foliated and schistose; a little farther away, in the cliffs, it is less altered, but shot through in two directions with white calcite veins.
To continue around the circle and head back, take the path that leads around the cliff top to your right, and crosses the back of the headland to come out behind the houses at which you began. Please have consideration for the private property you must cross on emerging.
These are Cambrian mounds known as thrombolites (meaning "clotted structure") that were the growth form of millions of tiny algae and bacteria. The furrows that contain mud-cracked material and radiate from the centre and down the sides may be drainage channels. These organisms are thought to have thrived in the tidal and subtidal zone of a warm, very salty sea, some being exposed at low tide, and covered at high tide, thus explaining the mud cracks. The larger ones may be several communities that amalgamated as they grew.
Where a mound has been eroded away, a circular depression is left in the flat layer below. A little farther around the point, the dolostone surrounding the mounds has not yet been removed by erosion, but the tops can be seen just emerging from the next lower layer.
When you look across the bay to the south, you can see another large colony of
thrombolites on the shore. If you drive back out to the highway and turn in at the next road
to the south, you can walk out to the small point where there is a fish hut built right on a
collection of mounds. Here the thrombolites are not standing as high, but they are more
numerous. Some seem to have a veil or mat of fossilized algae draped over them, partly
removed by erosion.
South East Labrador
Stops in southeast Labrador are reached by ferry from St. Barbe to Blanc Sablon, Quebec, and
then by Route 510.
From Blanc Sablon to Capstan Island, the sea cliffs and flat-topped hills consist of Cambrian conglomerate, sandstone, shale, and limestone that lie unconformably on Middle Proterozoic gneissic granite of the Grenville Province. The sedimentary rocks were deposited in riverbeds and in a shallow sea at the northwest margin of the Iapetus Ocean (see Plate Tectonics panel). The thick lower sections in the long sloping roadcuts are mainly sandstone. Thinner beds of shale and limestone overlie the sandstone, and can be seen near the L'Anse-Amour lighthouse and in quarries at higher levels.
Take the turnoff to L'Anse-Amour between Forteau and L'Anse-au-Loup, drive about 4 km, and park near the lighthouse. Walk down and along the shore to see fossils in the rocks on the beach and in the cliffs behind it.
Rock types include pink and red sandstone, red to purple mudstone, and medium- to thin-bedded grey and orange-weathering limestone. The purple mudstone contains rings and irregular blebs or fragments of white calcite. These are the remains of now-extinct, primitive organisms called archeocyathids, which once formed reefs similar to modern coral reefs.
Near the lighthouse, in the orange-weathering limestone, there is a large mound that formed as a reef in the Cambrian sea. Within the reef are layers and irregular masses of archeocyathids, which include pieces shaped like sticks, cups and plates. There are also other fossils and thin layers of sediment. The bedded grey limestone below and around the reef consists mostly of crinoid fragments. Crinoids are extinct; they looked like sea urchins but were anchored to the sea floor by long stems. Masses of crinoids resembled flowers growing in submarine "meadows" and they surrounded the archeocyathid reefs in the shallow sea. The fine-grained, grey limestone consists of millions of broken pieces from the stems and heads of dead crinoids.
The lowest sandstone, close to the bottom of the hill, is the most coarse-grained in the section. Westward up the hill, vivid purple, red and buff coloured sandstone beds alternate; some of the bedding planes are curved, reflecting the scouring action of strong, variable currents that deposited the sand. The sandstones are mostly crossbedded, another indication of strong currents. The often paler coloured, thicker beds tend to contain less mud, and some have fossil worm burrows. The colours and variety of patterns are spectacular. The purples and reds are a result of oxidation of iron in the sand around the time of deposition.
Toward the top of the hill, the beds are thinner and shaly. These finer grained sediments were deposited in deeper water as the sea invaded farther inland.
Note the deep-red colour of sand along the road east of Pinware. The sand was derived by glacial erosion of the red gneissic granite bedrock, and deposited by glacial meltwater in this broad valley. Work crews have used it to fill and smooth excavations during road and sewer construction in West St. Modeste.
By contrast, the sand banks and dunes west of L'Anse-au-Loup are a pale, delicate pink. They were derived from the paler buff, red and pink Cambrian sandstones.
The shorelines in the community and at Saddle Island, where the historic Basque whaling operation was located, are composed of dark grey gabbro deformed during the Grenvillian Orogeny. An outcrop of this rock forms the shore just east of the Visitor Centre. The gabbro is coarse grained and contains grey feldspar crystals up to 3 cm in length, as well as black pyroxene and biotite. It weathers to a lighter mottled greywhite, and is slightly magnetic.
Slabs of Cambrian sandstone from farther west on the coast have been used to pave the approach path to the Visitor Centre.
Newfoundland and Labrador Traveller's Guide to the Geology
Edited by: S. Colman-Sadd and S.A. Scott, 91 pp. + map, 1994