William Bay NP - Nature and Landforms

Denmark, Western Australia

The granitic rocks along the south coast of WA began to form about 1.5 billion years ago, making them among some of the oldest rocks in the world.

As two continents collided together, the South Coast rocks became part of the Albany-Fraser Oregon. 600 million years ago this was a massive mountain range, greater than the Himalayas. The mountains have long since been eroded away, so the rocks we see today are those which were deep down in the base of the range, close to the Earth's mantle.

The immense pressures and temperatures these deep rocks were subjected to during the mountain building event caused them to melt and recrystalise, forming granitic gneisses and migmatites, though for simplicity's sake they're often just referred to as granites.

Beaches, Dunes and Coastal Rocks

Rocky coastline, William Bay National Park

The beaches of William Bay National Park have fine, pure-white silica sand that squeaks underfoot. Most beaches along the coast are fairly narrow, backed by steep dunes or outcroppings of granitic rock.

Some of the mobile dunes behind Mazzoletti Beach are creeping back inland, covering bushland.

In several places, Waterfall Beach being the most obvious, small streams flow through the dunes and down onto the beach, carrying darker sands and soils that mix with the otherwise pure-white beach sand.

The granitic outcrops along the coast are well-weathered and dome-shaped or gently sloping. The Elephant Rocks and domed boulders of Greens Pool are the most striking examples of these rocks.

Evidence of volcanic activity can be seen at Elephant Cove. The eastern edge of the cove is lined with basaltic rock - the remains of a volcanic dyke. The long, straight cove was formed through erosion along this line of weakness. You can read more about the geology of the rocks around the cove on the Elephant Cove page.

William Bay National Park and Vegetation and Inland Landforms

Inland from the coast, the terrain is mostly undulating and densely vegetated. There are some tall, steep hills - the most obvious of which is Tower Hill - on top of which are outcrops of granitic rock.

A huge variety of plants grow in the national park, often with many different types intermixed across a relatively small area.

Most species usually found in the tall karri and jarrah forests are present in the William Bay along with the coastal heath species, but they've adapted to the tough coastal conditions of strong winds and salt.

Trees like karri, jarrah and peppermint grow shorter, and the peppermints are gnarled and bent, especially on hilltops. In the deepest valleys taller trees can grow, reaching the height of the surrounding hills and dunes.

Sprintime is the best time to see the wildflowers in bloom, but no matter what time of year you visit, there will be flowers to see if you keep an eye out for them.

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