What? A Geography Lesson? How Fun is That?
The Margaret River Region is in the south-western corner of Western Australia. It is bound on the west by the Indian Ocean, the south by the Southern Ocean and north by the more sheltered Geographe Bay.
The Leeuwin-Naturaliste National Park runs almost continuously along the western edge of the Margaret River Region. This park encompasses a hilly ridge covered in thick coastal bush and forest. The coastline to the west is fairly rugged, with rocky headlands and outcrops separated by white sand beaches.
It Used to be Attached to India!
The Leeuwin-Naturaliste Ridge is a dominant feature in the region. It consists of ancient granitic rock that is up to 1.5 billion years old and is the old core of a mountain range that formed when today’s India collided with it. When the two landmasses separated again about 135 million years ago, and India drifted north, the ridge was left behind.
Over the past 1 million years, extensive sand hills have been formed on top of this granite from the wind blowing in bits of shell, coral and other marine skeletons (which are all composed of calcium carbonate). As rainwater mixed with rotting plant material, it became acidic and percolated through these dunes, dissolving the calcium carbonate and redepositing it as limestone at the base of the dunes. This type of limestone is called the Tamala Limestone.
The Caves are Incredibly Special
Streams flowing underground above the granite bedrocks but through the limestone have given rise to hundreds of beautifully decorated caves, many of which possibly remain undiscovered because they have no access into them from above ground. The caves on the Ridge are quite unique because they formed from wind and rain activity, whereas most cave systems formed underwater in a marine environment.
The land to the east of the Leeuwin-Naturaliste Ridge is much flatter and formed by millions of years of sediment deposits from the erosion of land to the east.
Poor Soils are a Good Thing
The soils of the region were mostly formed from the weathering of granite to form loamy soils that are high in iron. These soils are low in nutrients such as organic matter and essential elements, and are perfect for growing wine grapes. Grape growing started in the 1970s and there are over 150 wineries today. The 3% of wines made here provide 20% of the boutique wines in Australia; the quality is that good.
It is also this nutrient-poor soil that supports a wide array of stunning wildflowers and majestic trees such as Karri, Jarrah, Marri, Blackbutt and Peppermint. The south west area is one of only 34 biodiversity hot spots in the world and nearly 80% of the plant species are found here and nowhere else on the planet. There are over 8000 species of flower in the South West, including about 300 species of orchids. Best wildflower viewing time is between August and November.