1. Conglomerate (Brigus Formation): a 550 million year old lithified beach rock. An ancient shoreline ran through this spot and is now exposed at the base of the 6 meter thick beach layers by the bridge. The beach deposit was formed from debris eroded from nearby cliffs made of volcanic rock, with some granite. Notice how well rounded the beach rock pebbles and cobbles are, just like those in modern beaches (see stop 7). Conglomerate beds dip at 10° downstream (NNW) and are overlain by poorly exposed, pink, red and green fossiliferous limestone and shale; all of these rocks form the Brigus Formation.

Close up of conglomerate showing well-rounded pebbles of former beach

View of unconformity, located along direction of arrow, downstream from road bridge. Conglomerate (cgl) above, rhyolite (rhy) and grante below

2. Downstream from the hard, weathering-resistant conglomerate, granite and volcanic rocks, the river winds its way through a narrow, steep-sided gorge cut in easily eroded shales. Manganese-rich nodular limestone beds are exposed in the river and mark the base of the overlying Chamberlains Brook Formation. The rock has been dissolving in the water to produce the pitted and cleft rock surface.

3. The flat areas of the river valley (stops 3-5) are formed from alluvium: sediment with a wide range of grain sizes deposited from the river when in flood. Note that the river meanders, and the meander has cut down ('incised') into the soft shale bedrock. The Chamberlains Brook Formation is mainly greenish-grey shale, a fine-grained sediment laid down in an ancient shallow sea. The shales weather quickly and are easily broken along their bedding planes, so that the bedding is easily seen in the cliff sections. Notice that the dip of the beds is consistently downstream, so that, proceeding towards the beach, we are walking across progressively younger rocks, and up the geological succession.

View of the steep-sided gorge downstream from the Chalet

View of 4b from across the river; arrow shows position of volcanic ash layer

4. The Manuels River Formation is mainly dark grey to black shale. It contains the most fossils, especially trilobites, though it is much more common to find bits of trilobites than whole specimens. Search among the loose debris for specimens. Hammering intact rock for specimens is not permitted. Note that the base of the Formation is marked by an ancient volcanic ash layer, a few centimeters of clayey material that was deposited from the ash of a distant volcanic eruption.

5. "The Flats". The elongate lagoon between here and the beach (stop 7) contains fine-grained, organic-rich muds, presently accumulating under more stagnant conditions.

6. Rusty weathering 'rottenstones' mark the transition to the youngest rock formation in the river section - the Elliot Cove Formation. This is another shale sequence but with sandstone bands increasing in frequency towards the mouth of the river, indicating that coarser sediment was carried into the sea in this area at that time.

View along the beach looking north to Chamberlains Head. Note several beach levels built by storms

7. The mouth of the Manuels River widens to form a lagoon fronted by barachois beach. The beach was formed by movement of material westward along the shore from the slowly eroding cliffs. These cliffs are almost vertical and made of glacial sediments. Notice the similarity in rock types between the cliffs and the beach. The shape of the beach is continually changing, most rapidly during storms. The barachois beach is cut at the west end by a narrow channel which is easily crossed (usually!). Sometimes the outlet is closed and the lagoon drains through the beach gravels. Before the headwaters of the Manuels River were diverted, there was a wider, deeper breach of the barachois beach.