IF YOU PARK AT THE GIVEN CO ORDINATES YOU MAY HAVE TO WALK A LITTLE BIT TO GET A GOOD VIEW OF THE MOUNTAIN AS YOU ARE LOOKING AT IT AS YOU NEED TO SEE THE RIGHT HAND END OF THE MOUNTAIN TO GET THE ANSWER.
Geological History of Boat Mountain:- The so called parent rock - more likely to be a basalt of Tertiary age ( 65 to 2 million years ago) was over flown with basalt of different volcanos that created a kind of valley bed with a thick basalt layer on top of it.
Changes:- Weathering changed the basalt often into rich red soil. In many areas rain in humid climates caused silica and other elements to leach out into the mottled layer underneath. The result is a hard layer with aluminium and high iron concentration. That is called ferricrete ( latin for cement). It is very hard and not a good fertile ground for vegetation. After the volcanic activity ceased, erosion removes lots of the basalt bed around the mountain, leaving behind the remnant ferricrete plateau on its top. What used to be the fertile basalt bed of the labva valley is now an elevated ferricrete plateau on top of the mountain, 'upside down' geology. Elevate ferricete plateaus are quite rare.
The slightly smaller leaves of the vegetation show how the plants cope with the reduced fertility of the soil. The remaining volcanic valley bed was much less affected by erosion etc because it has been a very big and relative flat low ground. Fossil Site:-The location of this fossil site is a place of rolling hills, some of the higher of which are capped with basalt from lava that flowed down valley floors about 25 million years ago.
The hardness of the basalt has resulted in them forming a fossil landscape as the softer surrounding rocks have been eroded down leaving them elevated above the areas that were originally above them, an inverted landscape. This has prevented the valleys that contained the swamps where the fossil deposits were forming from being eroded along with the former higher ground around them. One of these basalt capped hills is Boat Mountain, named from its resemblance to an upturned boat . The exposed sides of Boat Mountain allow access to some of the fossils that are protected beneath the cap. During the Early Eocene, about 45.5 million years ago, this site was a shallow swamp or lake. The Tingamurra Local Fauna deposits formed from freshwater clays laid down at this time. It is the only known site in the Australian part of Gondwana older than 24 million years that contains marsupial fossils. At the time the Tingamurra Local Fauna deposit was forming Australia was still part of Gondwana. It is also the only known fossil site in Australia from the beginning of the great diversification of mammals after the demise of the dinosaurs.
QUESTION: At the given co ordinates, which is outside of the declared Boat Mountain Conservation Park, looking at the Mountain towards the end towards your right at the top of Boat Mountain about the mid point and email me the answer to this question. What can you see that may looks out of place. May be erosion, may be natural or maybe man made. What do you think.
What is the most prominent geological feature. One email with answers for more than one geocacher will not be accepted.
If you wish to explore further you can drive to Hebbel Drive and go to S26 09.894 E151 58.254 then climb the 179 steps to the top and walk along the top of the mountain to the lookout. You will be in the Boat Mountain conservation Park. .
You can log your find at the same time as sending me your email but no email with the required answers within 3 days of the claim will mean the deletion of your log.
References: Australian museum Archives Queensland Museum Archives Queensland Conservation.
