Maraboon ~ Where the black ducks fly
Lake Maraboon is some 25km south-west of Emerald, and is Queensland’s second largest body of water by volume. It holds 1.3 million megalitres of water when full. Roughly three x the size of Sydney Harbour. The dam wall and spillway are named Fairbairn Dam. The dam provides a potable water supply and assists with flood mitigation.
Walk downhill from the parking waypoint. Be careful as rocks can be loose and slippery. Children should remain above or be closely supervised.
Sandstone sculptures
Sandstone is a lithified (transform into stone) accumulation of sand-sized grains up to 2 mm in diameter. It is the second most common sedimentary rock after shale, constituting about 10 to 20 per cent of sedimentary rocks in the Earth’s crust. The abundance, diverse textures, and mineralogy, of sandstone makes it an important indicator of erosion and depositional processes.
Texturally, sandstones consist of two components: (1) a framework composed of sand-sized grains and (2) interstitial (space) volume between grains, which may be empty, especially in modern sandstones. The most ancient sandstones may be filled with either a chemical cement of silica or calcium carbonate, or fine-grained matrix.
The principal mineral constituents are quartz, feldspar, and rock fragments. The relative proportions of these have implications, first for the source area, and second for the rate of deposition.
Sandstone comes in a myriad of colours from sparkling white, cream, pink and yellow, through to greys, brown and black. Iron oxide produces rich red seams in sandstone.
Sandstone is a durable and attractive natural building material.
Source: britannica.com and Wikipedia.
Logging requirements
You need to visit both waypoints. Please answer the questions below and message your answers to me, within a couple of days of your visit. You can log the Earthcache immediately.
Selfies taken at the lake may be uploaded to your log but are not required. Spoiler photos of the waypoints (sculptures) will be deleted.
Waypoint 1 (posted coords):
1. Standing with your back to the lake, look at the sculpture. Briefly describe it?
2. There is something smooth, embedded in the sandstone around 1 metre off the ground. What are these, and how do you think this occurred? (embedding)
3. There is a distinctive horizontal seam low on the structure. What colour is it, and what do you think it is composed of?
Waypoint 2:
4. Facing the lake, describe the large (standalone) sandstone sculpture below you?
5. How do you think this sculpture was created?
Before you go... Look up! There are wedge-tailed eagles nesting around the lake.