The city at Macquarie Harbour is the entry to the Franklin-Gordon Wild Rivers National Park and stopping place of the modernized West Coast Wilderness Railway. The town was a port to a small fishing fleet and is now a great destination for tourists. If you are visiting the Henty Sand Dunes you can rent sand boards and toboggans in the city.
B :: development
This formation has developed within the last 10,000 years during the Quaternary period. These massive sand dunes are 15 km along the coast line and reach heights of 30 meters. Its main creation factor is a wind current, known as the Roaring Forties. These are uninterrupted winds at the latitude 40° S, which brought sediments and took part at forming the dunes. The Roaring Forties can create some of the strongest winds on earth, especially in Tasmania, New Zealand and some parts of South America, where they are uninterrupted. Thou the wind was critical in creating these huge sand dunes.
This empbayment is like a amphitheater in that it creates a concentration of sediments. In former times local mountains were glaciated and created glacial rivers like the Henty River and its small side rivers and creeks. Their ice margin supplied much of the dunes’ sand. Most of this area is today underlain by Tertiary and Quaternary deposits:
Tertiary: sandstones, siltstones, clays // Quaternary: sediments from marsh, swamp deposits, mobile and stable dune sand, beach sand, gravel
The river alluvium, sand dunes and gravels represent the Quaternary system in the area. The alluvium can be seen on the margins of the Henty River and on marshy flats. The sand dunes occur extensively between Hemine and the Henty River. They have their greatest development at the northern end of the Ocean Beach, where they extend inland for about a quarter mile. The gravels are most visible near the coastline near the mouth of Montagu Creek. It is in this area, that one can see a section of thick inteterbedded fine sands, grit and coarse gravels. The section is likely deposits from Montagu Creek later eroded by the sea.
C :: logging conditions
To log this cache please send us your answers for the following questions via the GC-contact form. You don´t have to wait for a permission, but we will contact you if there are any problems with your answers.
- Describe the ingredients and size of the sand in your own words.
- Try to find out the main wind direction and the aeolian dune shape.
- optional: Please take a photo of you and your GPS and attach it to your log.