Geology Locations in the Southern Forests

Geology: Pemberton, Northcliffe, Walpole and Windy Harbour

Black Point: D'Entrecasteaux National Park.

One of the most spectacular sites to visit in D'Entrecasteaux National Park is Black Point: a massive outcrop of hexagonal basalt rock columns formed 135 million years ago by volcanic lava flow oozing into the ocean when Gondwanan continent broke up.

Black Point

Volcanic. Until quite recently the volcanic series was considered to be only represented by a basaltic sheet in East Kimberley and an outcrop of the same rock at Bunbury in the south-west. Later investigations, however, proved that it is of considerable extent and importance.

These rocks evidently belong to two distinct periods, the one consisting principally of andesitic rocks and the more recent of basaltic. They both occur in the form of dykes, necks, sheets, and flows, and are often vesicular, whilst the andesites are sometimes amygdaloidal.

Basalt occurs as extensive flows, forming the Great Antrim Plateau in the East Kimberley district, which extends into the Northern Territory of South Australia, and is also met with at many points in West Kimberley, but this latter has not as yet been geologically mapped.
At Bunbury it occurs in sheet form, assuming the columnar structure upon the beach, whilst southward from this point outcrops are met with in the Lower Blackwood River, and at Black Point upon the coast.

DPaW Black Point

Geology Black Point

Beedelup Falls: Granite rock - Beedelup National Park.  

Beedelup Falls is a series of rocky cascades flowing down to Lake Beedelup and Karri valley Resort. Ancient granite 2.4 billion years old.

There are giant stands of Karri as well as small pockets of Jarrah and Marri trees.

There is a 300 metre walk trail from the car park and a 4.5 km moderately hard walk around Lake Beedelup and Karri Valley Resort. The Bibbulmun Track skirts the northern side of the lake passing through Beedelup Falls enroute to Beedelup Hut, some two kilometres from the Falls.

DPaW Beedelup Falls

RAC 10 Best Waterfalls

 

Cascades: Granite rock - Gloucester National Park.

Granite melted down and reformed when continental plates collided 1.2 billion years ago. 

In the Gloucester National Park the Lefroy Brook transforms from a gentle flow in mid summer to a raging torrent in winter with water tumbling over the Cascades. The Cascades is a fantastic place to visit all year round. In summer, it’s a cool, shady place for a picnic and in winter, the Lefroy Brook is an impressive sight as it plunges over the Cascades.

DPaW Cascades

WesternAustralian Travellers Guide

Cascades bubbling over

Yeagarup Sand Dunes: Mobile sand dune system - D'Entrecasteaux National Park.

The Warren dune chronosequence, similar to the situation on the Swan Coastal Plain, comprises three dune system. The youngest system is up to 7,000 years old - the age of "the ancient Yorkshire Downs". These young dunes are alkaline and relatively rich in phosphorus and calcium. The next system is from ca. 120,000 to 500,000 years old; the soil is slightly acidic and nutrient impoverished, particularly low in phosphorus. The oldest dunes are up to 2 million years old; they are severely nutrient-impoverished. The plant diversity increases as the soil phosphorus levels decline to the very lowest on Earth. A key difference between the Warren and Jurien Bay chronosequence is the climate, which is a lot wetter on the south coast where the Warren chronosequence is located

Yeagarup & Warren Sand Dunes:

 

Mt Chudalup: Granite rock - D'Entrecasteaux National Park.

Mt Chudalup is located within the D'Entrecasteaux National Park, a narrow strip of land 5 - 20 kilometres wide which stretches along the south coast for more than 130 kilometres between Augusta and Walpole.

A significant landmark in the south of the wild and isolated D’Entrecasteaux National Park, Mt Chudalup offers a great walk and fantastic views over the surrounding landscape and out to the coast . A huge block of granite, Mt Chudalup is known as a monadnock, which is a large isolated hill above a generally flat plain.

Mt Chudalup

DPaW:

Mt Chudalup W Eiby

Mt Chudalup on top looking towards Windy Harbour DEtrecasteuax National Park Wendy Eiby 3

Point D'Entrecasteaux: Consolidated limestone cliffs.  D'Entrecasteaux National Park.

The Geology of Australia

Geological Formations. The known geological formations of Western Australia are as follows: -

Crystalline                   Igneous origin; Metamorphic origin (Pre Cambrian?).

Palaeozic                    Metamorphic origin  (Pre Cambrian?); Cambrian, Devonian, Lower Carboniferous and Permo-Carboniferous.

Mesozoic                     Jurassic.

Recent                        Superficial and marine deposits.

Volcanic                      Sheets, flows and necks.

The Recent deposits consist of raised beaches at various points around the southern and western coast and coralline limestones and sandstones, which sometimes contain fossils or casts of shells of existing types, thus proving this section of the coast to be rising.

DPaW:

D'Entrecasteaux National Park

Hema Maps D'entrecasteaux National Park:

 Windy Harbour cliffs Salmon Beach

Granite Gneiss at Windy Harbour beach. D'Entrecasteaux National Park.

Crystalline Series. The Crystalline rocks, which consist of granite, gneiss schist and greenstone, cover an estimated area of 650,000 square miles, or a total of two-thirds of the superficial extent of the State, and may be divided into three groups, the first of which comprises the granites, gneissic granites, and schists of the south-west division; the second, granites, gneissic granites and greenstones of the central and eastern portion of the State; and the third, granites, gneissic granites, schists and greenstones of sedimentary origin of Kimberley and the north-western districts. 


The first group is represented by a belt of gneissic granites and acidic schists, with intrusive granite and pegmatite veins, diorite dykes and quartz reefs, which occupy practically the whole of the south-western land division of this State; they occur in a belt that has a course a little west of north, extending from the south coast to the Murchison River, being about 200 miles in width at the south, extending from Point D'Entrecasteaux to doubtful Island Bay, whilst to the northward as it impinges upon the west coast it narrows down to 125 miles. 

Upon the western side of this belt, these rocks form a bold escarpment to the seaward, called the Darling Ranges. This face is evidently a fault line, since rocks belonging to a much more modern period are exposed in places at their base, where the talus covering them has been removed or pierced by wells.

This range forms the edge of an interior tableland, but does not attain any considerable elevation; the highest point, Mount William, is said to be 3000 feet above the sea level.

The question as to whether these rocks are of sedimentary or igneous origin has not yet been determined, but the uniformity of their foliation and apparent bedding, with the occurrence of graphite, would almost favour the former. They have so far proved of economic value only at two points, viz.: Northhampton at the north, where lead and copper lodes are found associated with porphvritic diorite dykes, and at Greenbushes at the south, where tin deposits occur in pegmatic and griesen dykes. The diorite dykes which have been intruded into these rocks are generally of an aphanitic character, whilst the quartz reefs are large and often contain marcasite in considerable quantities, but, although generally carrying both gold and silver in small quantities, discoveries of a payable nature have not yet been made.

Upon the south coast, and also upon the eastern side of the Darling Range, a series of magmatic intrusions of granite are met, which upon the coast form bold bare headlands and islands of rounded and polished dome-like shapes or fantastical ruined forms, and this character is maintained by the island outcrops, which generally follow the lake margins between the Great Southern Railway line and the goldfields.

West Cliff Point: Consolidated Limestone - D'Entrecasteaux National Park.

The Recent deposits consist of raised beaches at various points around the southern and western coast and coralline limestones and sandstones, which sometimes contain fossils or casts of shells of existing types, thus proving this section of the coast to be rising.

Limestone cliffs Windy Harbour Pt DEmtrecasteaux 

Northcliffe George Gardner Rock and Fossil Collection. Northcliffe Pioneer Museum

The George Gardner exhibition in the Museum’s mill cottage displays Aboriginal tools used dating back 8000 years, fossils from 3000 million years old and 1200 rocks and minerals from around Australia and overseas. The collection also includes the George Gardner photographic record of all native wildflowers growing in the Northcliffe region.

Northcliffe Pioneer Museum

Working Life Museums:

Mount Frankland: Granite dome - Mt Frankland National Park

Mount Franklandis a massive granite dome that rises to 433m above sea level, sticking up above the surrounding Karri Forest. It covers the low granite hills to the north of the town of Walpole and is covered largely by forests of karri(Eucalyptus diversicolor) and red tingle (Eucalyptus jacksonii). The steep one kilometre walk takes you up Mount Frankland combining a walk around the base of the granite mount, surrounded by towering karri forest and superb summit views this is a trail sure to impress.

DPaW Mt Frankland

Mt Frankland bushwalking Monodock 6

Mt Frankland Wilderness Walk 4 

 

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