Welcome to Ross and this Earthcache. This is a geocache where there is no physical container to find - instead you are looking at a unique geological feature of the area and need to answer questions, as well as posting a picture, in order to claim the find.
A lot of Tasmania is geologically known for its Dolerite. But here in Ross at this historic Quarry you will marvel at its beauty and be struck by the many vibrant colours of Sandstone. Exact dates of the quarry’s history are difficult to pinpoint, however archaeological research indicates it was most likely used from the late 1800s to around 1910. It is possible that up to 1200m3 of stone has been extracted from this quarry, which is about enough stone to build 10 four-bedroom cottages.
Since the stonemasons ceased working on the quarry it became overgrown for many years. Ross locals understood the significance and in 2015 project work began to turn it into a historic area that was officially opened in October 2019.
The quality of Ross sandstone was superior and well-known across the world as referenced in this newspaper extract:
‘The Ross freestone is world known for its excellent qualities, both as a building stone and for grindstones, monumental stones etc and a sample of this stone was recently awarded first prize at the British Empire Exhibition at Wembley, and the same stone was awarded a certificate of merit at the Pennsylvania Exhibition, United States.’ – Daily Telegraph (Launceston, Tas. : 1883 – 1928), Thursday 22 July 1926, page 2.
What is Sandstone?
Sandstone is a common clastic sedimentary rock found in basins around the world. It forms when sand-sized particles are moved by water sources like rivers, lakes, and streams, then settle and become cemented together with other materials such as rock fragments or minerals like quartz. Over time, layers of sediment build up, and the pressure from newer layers compacts the older ones—a process called lithification. This compaction, along with natural cementing agents like calcite, clays, or silica, binds the particles into solid rock.
Sandstone comes in various colours, most commonly tan, brown, yellow, red, grey, pink, white, and black.
The pale fine grained Sandstone of Ross was formed over millions of years during the Triassic period (Approximately 51 million years, from 251.9 million to 201.3 million years ago).
Much of Tasmania was covered by a layer of sandstone, up to 300 meters thick, that formed in this way. The colour and character of the stone is varied but is known collectively as the Parmineer supergroup.
In some areas other rock formations, such as dolerite of the Western Tiers and Ben Lomond, lie over the sandstone. In the midlands, and in Ross, the sandstone remains close to the surface. Where surface outcrops of the sandstone occur, such as along this ridgeline, stone can be readily quarried.
The stone is of various qualities, extending from a yellow-grained stone, much resembling wood, to a magnificent grey freestone, from which the grindstones are produced.
The darker coloured bands visible on some of the stones are known as Leisegang rings and are due to the presence of iron oxides.
Honeycomb weathering is another natural feature visible in some stone. Honeycomb weathering in sandstone is primarily caused by salt weathering, where salt crystals growing within the rock's pores force the rock to fracture and disaggregate. This process is often exacerbated by wind and variations in moisture and temperature.
Something else of interest;
Many numbers of methods were used to extract the sandstone.
Channelling
Quarrymen cut channels into the rock using picks to mark out where blocks of stone would be taken. The quarry shows clear evidence of channelling.
Drilling
Small holes were drilled into the channel to site the wedges or leavers used to split the rock.
Wedging
Wedges or levers would be driven into the drill holes using a hammer or mallet. The force would fracture the block away from the quarry face. Subtle diagonal lines on some of the vertical surfaces where blocks of stone have been removed are evidence of wedging.
Blasting
Blocks could be removed by blasting, a row of small holes were drilled into the stone and blasting powder was packed into the rows, then detonated. The blast would fracture the block away from the body of the stone.
Sawing
Stone saws were used to cut raw blocks of stone down to the size required and to square up the block.
Picking
Stone building blocks were often finished by picking with chisels used to create a flat surface, leaving small repeated depressions in the face of the block. Some of the surfaces in the quarry show signs of picking.
Look around, you can see evidence of the above in places.
To claim this Earthcache please complete the following tasks and email your answers to the questions using the email function of the gc.com profile page;
Stage One - S42 02.201 E147 29.981 At this waypoint (GZ) you will see layers of different colours.
Q 1) What colours do you see and what do you think has caused this colouring?
Q 2) How thick are the visible layers in the sandstone?
Q 3) Are the grains in the sandstone fine, medium, or coarse? Describe the texture and their size in millimetres.
Stage Two - S42 02.200 E147 29.963
Q 4) Here you will note a particular type of weathering at the base of the face. Describe this different type of weathering and how you think it was formed.
Stage Three (REQUIRED TASK) – S42 02.200 E147 29.975
From this waypoint, take a non spoiler photo including yourself and/or your geocaching name and date facing towards the town of Ross. Include this photo with your answers and your log to prove that you have attended the location. Preferably the photo will show how happy you are to find this Earthcache.
The nearby Ross Bridge is one of Australia’s finest examples of sandstone bridges
You are welcome to log your find straight away to keep your TB's and Stats in order but please message us with your answers within a couple of days. We will at some stage review your answers but we may not always reply. If there are any concerns or your answers need extra work we will contact you. Logs with no answers and photo and who do not fulfil this Earth Cache requirements will have their logs deleted without notice.