Four Short Natural History Lessons About The West Coast

Wherever you are in the West Coast you are in one of the world’s interesting natural environments. We have listed 4 natural history lessons on this area.

Wherever your West Coast accommodation is located, you are in one of the world’s most interesting natural environments. 

Glaciation, erosion and wild weather have shaped the landscape of the West Coast; rainforests, swamps and wide alluvial plains can be found in close proximity to each other; and the ocean and the rivers continue to mould and alter the countryside.  For any visitor to the West Coast, a knowledge of it’s natural history will help you to better appreciate this fascinating region of New Zealand. 

Here are four short natural history lessons about the West Coast.

Geology.  The West Coast region lies along the boundary between the Pacific and Australian crustal plates, which are slowly grinding against each other. The stress of this collision causes rising mountains, earthquakes and landslides.  The boundaries of the two colliding plates runs from south to north up the western side of the South Island. 

The seam where the two meet is marked by the Alpine Fault. This huge feature (it is actually visible from space!) forms the western edge of the Southern Alps.  Land on the eastern side of the fault is rising at the rate of about a centimetre a year, making it one of the most rapidly rising mountain ranges in the world.  At the same time, the rocks on each side of the fault are gradually sliding past each other.

Those on the western side of the Alpine Fault have moved northwards about 480 kilometres compared to those on the eastern side.  Rocks found in South Westland are identical to those found in the Nelson region at the top of the South Island.

Flora and Fauna. Rising from the wild sea through sub-tropical rainforest to towering mountains, the West Coast is home to a unique and varied collection of flora and fauna.  Near the coast, flax grows in abundance and dense lowland rainforest grows thickly on the swampy ground.  As the land rises and the climate changes, the rainforest gives way to a tangle of sub-alpine scrub, tussock-lands and alpine herb fields. 

Above these, only hardy lichens can survive the brutal conditions of the high tops.  The dense podocarp forests, with their towering matai, kaihikatea and rimu trees are often splashed with colour as the southern rata provides a brilliant display of red flowers in January and February.  At other times of the year, creamy kamahi flowers, the orange, red or blue berries of native fuchsia and coprosmas, along with the yellow and white flowers of the native clematis, all add colour to the deep greens of the rainforest. 

The lagoons, forests and high alpine basins are the habitat of virtually every mainland bird in New Zealand, including the only known nesting place of the Kotuku (white heron), which nests around the swampy lagoons of Okarito.  Bellbirds, tui, New Zealand wood pigeon, fantails, bush robins and the comical kea can all be spotted without too much effort.  Kiwi forage in the forest at night but you need to be very patient to see or hear them. 

The Coast’s rivers teem with fish, eels and the legendary whitebait while hunters can find introduced thar, red deer and chamois in the hills.

Glaciers. Glaciation has been one of the dominant forces in the shaping of the West Coast’s landscape.  High in the Southern Alps, snow collects in basins known as cirques, where it slowly compacts until it turns into ice.  As the ice grows deeper and heavier it begins to slide downhill, like slow-moving rivers, carving out u-shaped valleys as it goes. 

There are hundreds of glaciers on the western side of the Southern Alps, most of them hidden by the jagged peaks and teetering ridges.  But two of them, Fox Glacier and Franz Joseph Glacier, flow down almost to the sea.  Fed by four alpine glaciers, Fox Glacier falls 2,600m on its thirteen kilometre journey down to the coast, and is one of only a few glaciers in the world to terminate amid lush rainforest only 300 metres above sea level.  Its neighbouring glacier, the twelve kilometre-long Franz Joseph Glacier, is fed by a twenty square kilometre snowfield and terminates nineteen kilometres from the sea. 

Having retreated several kilometres between 1940 and 1980, the Franz Joseph Glacier entered an advancing phase in 1984 and since then has advanced at the phenomenal (at least by glacial standards) rate of seventy centimetres per day, which is around ten times the rate of most glaciers.

Weather.  The West Coast is known affectionately by New Zealanders as the “Wet Coat.”  This is by far the wettest place in New Zealand and it is the weather that has been the dominant force in shaping the landscape of the West Coast as you see it today. 

Lying as it does on the eastern edge of the Tasman Sea, the West Coast is in the path of prevailing westerly winds which pick up moisture as they move across the surface of the ocean.  When these moisture-rich air masses hit the barrier of the Southern Alps, they begin to rise and as they do so, the moisture condenses (just like the moisture which condenses on the inside of your shower) and falls as rain.  And oh what rain!  Rainfall on the West Coast is measured in metres!!  It is common for half a metre of rain to fall in an afternoon.  In the hills behind Hokitika, lies the catchment of the Cropp River which receives eighteen metres of rain per year: the wettest place in New Zealand. 

But it’s not all about rain.  The West Coast has a mild climate and in winter, when the westerly wind patterns are at their lowest ebb, the coast experiences long periods of sunny weather.  So enjoy the West Coast’s weather and remember that the weather, along with the other elements of its natural history, makes the West Coast of the most unique places in the world…just remember to bring a coat!