The Landsborough Sandstone geological Geological History The uplifting of the metamorphic rock (Rock that changes, through the process of heat and pressure), was followed by one or more major volcanic episodes resulting in extensive areas of the land surfaces covered by lavas and fragmental rock.
These lavas were viscous (sticky), slow moving rich in gases. Since that time, erosion has removed a large part of these rocks and what remains is a complex sequence of overlapping sheets that is difficult to decipher. These remnants, named the North Arm Volcanics are now exposed between Maleny and Eumundi. The sands and gravel formed by the erosion of the older rocks were deposited over broad plains to the south, east and north east of the Maleny Plateau.
Great thicknesses of sediment accumulated in sedimentary basins which subsequently consolidated and hardened to form the sedimentary rock known as the Landsborough Sandstone. It comprises of variable late Triassic (245 – 210 Million years ago) to early Jurassic (210 – 65 Million years ago) sedimentary rock including Sandstone, Siltstone, Shale, and Conglomerate. In the middle Tertiary period (25 Million years ago), numerous dome-like plugs of Rhyolite and Trachytes magma intruded into the higher rocks as volcanic vents or subsurface bulges. The erosion of enormous volumes of the softer sedimentary rock (sandstone, Landsborough Sandstone), has revealed the Glasshouse Mountains in the South.
Below the Landsborough Sandstone is a distinct layer if Igneous rocks, indicating this is older than the Sandstones above the original bedrock. This layer of igneous rocks include Rhyolite, Trachytes, Agglomerate and Basalts.
NB. You will have to use caution when proceeding and keep eye on the younger kids
, It is quite a easy walk, but there are some rock pools and jumps needed to get to the location along the rocks, and its essential to attempt this during low tide as that when the tide is in its more treacherous, and will be very difficult to get to the cache location.
I don’t think the GZ will be accessible in high tide. And you will not be able to examine the area to answer the questions. To check the tidal times just visit - http://tide-times.com.au/localtime_QLD/Sunshine_Coast/Beaches/Kawana_Beach.html
There are some really strange rocks/minerals in the area, they are mostly Basalts, Trachytes and agglomerates inbedded into the sandstones At the co ords specified above, take a good look around, and try to find a rock that does not seem to fit in the area, makes you wonder what else could be in the area. It will be possible to break a small piece of it off to examine, but it won’t be necessary.
To log find - Please mail answers and log the find, you may snap a pic if you like aswell
Q1 – What colour is the rock that you should be standing on at GZ?
Q2 – What is the colour of the cliffs?
Q3 – What has happened to the cliff face over the years of erosion?
Q4 – What has happened to the rock on the floor from Q1, what does it look like?
Happy hunting and learning