Moura lies within the central Queensland sandstone belt which covers an area of approximately 82 000 square kilometres. Moura also lies in the Baralaba Coal Measures on the south-eastern flank of the Bowen Basin. This coal is of permian-age and contained in five major seams that average 3.5 – 4.0m in thickness, and dip at 5–12°.
Coal has been mined at Moura since 1961, making this one of the oldest operations in central Queensland. Moura also hosts Australia's first commercial coal-bed methane recovery operation.
Each year, Dawson mine produces coking, soft coking and thermal coal, using open cut and highwall mining methods. Coal is railed to Gladstone for export to Japan, South Korea, Taiwan and India.
However, to reach the coal they must first remove the thick layer of predominantly sandy rocks of the Clematis Sandstone above it. The Clematis Sandstone consists mainly of white to yellow-brown medium-grained micaceous quartz sandstone but can also be pink. The thickness of the Clematis Sandstone ranges from 30m up to 300m in the Dawson Range. The sandstone is 180 million years old and is also extensively quarried in the Moura region.
The perfectly round holes, like the ones in these rocks, occur as part of the open cut mining process when the rock is drilled prior to blasting the overburden above the coal seam. They are 28cm in diameter and are a strong reminder of the long history of mining in the area.
But what is the significance of these 'holey rocks' being used as markers in this location?
GPS is a space-based navigation system that provides location and time information in all weather conditions where there is an unobstructed line of sight to four or more GPS satellites which are orbiting the planet.
You use your GPS every time you go looking for a geocache. The coordinates you travel to use latitude and longitude. But do you understand the science behind it? This earthcache will make more sense of what the GPS is doing for you.
Unlike latitude, which has the equator as a natural starting position, there is no natural starting position for longitude. Each degree of longitude is divided into 60 minutes, each of which is divided into 60 seconds. A degree of latitude is always 60 nautical miles or about 111km, while a degree of longitude varies from 0 to 111km.
Meridians are imaginary lines that run around the earth from pole to pole. The global position of a meridian is selected by degrees of longitude east or west of the prime meridian (0 degrees) which runs through Greenwich, London. Greenwich Mean Time (GMT) is the average time it takes the earth to do a full 360 degree rotation once every 24 hours. This means that every 15 degrees of longitude between places on earth equates to a one hour difference in time. The 150 degree East Meridian, where you are standing, is exactly 10 hours ahead of GMT: London Time.
GMT was introduced in 1844. At midnight on the 31st January 1895, the legal time in the eastern states of Australia was synchronised to become known as Eastern Standard Time (EST). This brought Australia in line with standard time that was recognised world wide.
At the coords is the midpoint of the EST zone where the sun rises at exactly 6.00am and sets at 6.00pm twice a year at the equinox on 22nd March and 22nd September.
As of 2005 Standard Time is now defined by reference to Coordinated Universal Time (UTC). UTC is a high precision atomic standard time. This is achieved by approximately 300 atomic clocks in over 50 national laboratories throughout the world monitoring the world time. So although GMT is no longer the main reference for time, the 150 degree meridian remains an important reminder of our history.
You may log this Earthcache straight away but then please email your answers to the questions to the CO. We will contact you ONLY if your answers need extra work. Logs with no answers sent will be deleted. The answers can be found by observing the landscape and a bit of research.
1. Take a close look and feel the texture of the rock pillar at GZ. What kind of rock is it?
2. Is it an example of igneous, sedimentary or metamorphic rock?
3. What does GPS stand for?
4. What does equinox mean?