Many of the coves of Bonavista Bay and eastern Trinity Bay are open to the sea to the northeast and as a result, strong storms with northeast winds can be severe here. Waves driven into the coast commonly reach up to 6 m (20ft) above normal sea level, lashing and eroding the shoreline. In areas where the bedrock slopes into the sea, sediment is swept off by the waves, forming smooth, polished rock platforms, which at times are very slippery.
Although the waves appear to batter the coastline, most of the erosion takes place above sea level. Sea spray, rain, and snow infiltrate the cracks and joints of the exposed rock. When the water freezes, it expands and forces the rocks apart. Freezing water generates almost 5 times as much force as is required to break the hardest rocks of the Bonavista Peninsula (the conglomerates and sandstones), and thus even the land’s toughest rocks are no match for frost action. Over time, the frost wedging creates the stacks, sea caves and arches which are all visible along the coastline.
Sea caves form where frost wedging operates to carve a cave extending from the shoreline inland. In some places, a small hole develops in the roof of the cave. Waves entering the cave shoot water upwards through the hole, forming a spout. As erosion proceeds, the roof of the cave may collapse, leaving a tunnel extending inland from the shoreline to an open well where the cave roof has fallen in. The Dungeon, near Bonavista, is an excellent example of a collapsed cave.
Isolated gravel beaches, flanked by rock cliffs, are called pocket beaches. These short and narrow beaches are associated with steep, high cliffs and are common on the Bonavista Peninsula. Along these cliffs, intensive frost wedging occurs within the areas subjected to sea spray. Many pocket beaches are marked by high energy wave conditions even during seemingly calm days. The steep gravel slopes, both on the beach and directly offshore, are unstable so be careful when you walk along these beaches.
Rogue waves can cause problems. A rogue wave forms for no apparent reason, causing the level of water to change quickly. Some mysterious events, where the water level in harbours has dropped by more than 2 m (6ft) in less than a minute, followed by waves striking the shoreline as much as 6 m (18ft) above normal sea level, all occurring within 5 minutes on calm days and evenings, have been attributed to the arrival of rogue waves. Ask the residents about the changes in the coastline!
Sea Levels
During glaciation, sea level was lower than at present around eastern Newfoundland because large volumes of water were frozen in the major glaciers, including the one covering the Bonavista Peninsula. As the ice began to melt, sea level rose throughout eastern Newfoundland. Sea levels up to 35 m above the present shoreline are recorded. The weight of the glaciers caused the land to be depressed when it was covered by ice. After the ice melted, the land remained depressed for a time, allowing the sea to flood in. Eventually, however, the removal of the great weight of ice allowed the land to gradually rebound. The Bonavista Peninsula under the weight of the glacial ice was like a spring compressed by a large boulder. Once the boulder is removed, the spring will expand. When the glacier melted away, the land expanded (or rebounded), forcing the sea to retreat. Sea level fell around most of the eastern Newfoundland coastIn the last 6,000 years, the sea has risen again and part of this change reflects the ongoing movements of the crust in response to glacial disturbance. The other factor is the change in the amount of water in the sea, due to the melting of glaciers in Greenland and Antarctica. As a result, over the past 6,000 years sea level has risen steadily to its current position. All of the coastline of eastern Newfoundland is currently submerging. Today, the sea is rising by about 2 to 3 mm (1 inch) each year around the Bonavista Peninsula. Each year, there is just a little less land.
Coastal Temperatures
The temperature of the Bonavista Peninsula is affected by the cold Labrador Current which runs slowly offshore. This current is extremely slow, moving at only 2-3 km each hour (1-2 mph) - a lobster swims faster! Water temperature during August (the warmest month) is only 10 -12 degrees C (50-55 F), so the water is usually cooler than the land. Winds commonly blow from the sea to the land, bringing cool, moist air to the shore and restricting tree growth, apparent from the tuckamore trees, a low lying spruce or fir tree dwarfed by its coastal exposure. For the hiker, appropriate wind and rain wear is recommended.