The Hummock EarthCache
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An easy to drive to location with a magnificent lookout over Bunderberg.
The sloping hummock is the highest point in Bunderberg.
This district is at the northern edge of Hervey Bay, which opens out at the northern end of the Great Sandy Strait, discovered by Matthew Flinders in the Norfolk in 1799. He named an extinct volcano, the only hill of this area 'Sloping Hummock', now called 'The Hummock'. Captain Flinders returned to this area in 1802 in the Investigator while heading north on the second phase of the great voyage of circumnavigation.
Hummocks are rounded or conical mounds within a volcanic landslide or debris avalanche deposit. Hummocks contain a wide range of rock debris, reflecting the variation of deposits that previously formed the flanks of the volcano. Some hummocks contain huge intact blocks tens to hundreds of meters in diameter. Some of the original layering of lava flows and other deposits can be seen in these large hummocks, but most of the large rock fragments are thoroughly shattered. In other hummocks the rock debris is thoroughly mixed as if the material had been in a blender and thoroughly mixed together.
The Hummock for this earth cache is a low volcanic hill between Bargara (on the coast) and Bundaberg (on the Burnett River floodplain). The area surrounding The Hummock has a high agricultural productivity, with sugar cane making up most of the farmland. The land on either side of the river is made up of alluvial soil. Closer to the Hummock, the fields are derived from basalt (a rock formed from cooling lava).
Past volcanic activity has left basalt rocks, rounded by wave action, scattered along much of the coastline, especially headlands. As well, the Hummock, clearly visible from sea, is the centre of an area of rich, red soil, clothed in fields of sugar cane. Along this coastline, varied vegetation communities show responses to their environment, and important species of marine reptile nest in dunes behind the beach, posing management challenges.
The hummock is close to the river mouth, the sugar mill is located to receive sugar cane from surrounding farm land, and to transport products out by ship. Near the mouth of a major river, the flood plain is a wide, flat area, built up over thousands of years as flood waters flow over the plain and alluvium (mainly silt) settles, raising the plain a little each time.
The eruption for this hummock occured about 1 million to 900000 years ago. The erupted basalt lava flowed west to Bundaberg, south to the Elliot river and east to the Bargara coast then eventually flowing out to sea.
Looking out to the east the volcanic crater rim is the highest, water reservoirs and radio towers can be viewed when you look at in that direction. Around the hummock area fragments of lava, which were possibly erupted bombs can be seen. These show versicles (gas bubbles) and ropy surfaces (pahoehoe lava). Pahoehoe lava is caused by partially consolidated lava on the top of a flow being dragged along by liquid lava beneath.
Logging requirements:
1. OPTIONAL: Draw a sketch of the hummock. Indicate the approximate height and thickness of the rock, texture and prominent colours. Email your drawing to me.
2. What colour is the soil around the hummock? Why do you think it is this colour?
3. What part of the volcano do you think the hummock is from? Why?
OPTIONAL : post a photo of the hummock with your GPS in the picture.
Please email me your answers. You can log your find before receiving a reply but if you do not provide enough accurate information your post may be removed.
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