Conran Capers [East] EarthCache

This Earthcache is a six-in-one multi cache in a coastal area of immense beauty and cultural significance. It is supported by the Geological Society of Australia and was written to celebrate Earth Science Week and facilitate the Totally Spatial! project run by the Snowy River cluster of schools.

Cape Conran and surrounds is a fabulous area to visit. It has beautiful scenery, great beaches, interesting history and fantastic geology.

This area is part of the Victorian National Parks system and is managed by local rangers. National Parks are special protected places so please obey all signs and requests from rangers and be sure not to take specimens or disturb cultural artifacts

On the east side of Cape Conran proper is the East Cape area that includes the great picnic spot of Sailor’s Grave. To find Sailor’s Grave navigate the roads until you reach 37^o 48.147S 148^o 44.480E. At this point you will find an explanatory sign or two about the local environment. One of these signs mentions the geology of the off shore reef. There is no mention of the on shore geology.

Please plan your visit carefully. Times of high tide may put some outcrops underwater or with reach of wave action. Whenever walking on rocky shores always keep an eye out for unusually large waves.

The first waypoint beyond the carpark at 37^o 48.155S 148^o 44.514E may put you under water; it depends a bit on the tides! This outcrop is the first of several featuring interbedded turbiditic sandstone, slaty mudstone and some thin bands of chert. These sediments were originally deposited in deep water beyond the continental shelf. Mudstones and cherts are formed from fine grained sediments raining down from above. The turbidites are formed from packets of sand that developed on the shelf. However, they sometimes were dislodged and then rushed down slope, off the shelf, and spread out on the seafloor below. Rare fossils elsewhere indicate these rocks are of lower Ordovician age. These rocks have been through a major folding event [maybe during the Silurian] and are no longer lying horizontal. Where bedding is visible it seems close to vertical. The line across the landscape made by the edge of these rocks is called the strike.

The next waypoint is at 37^o 48.221S 148^o 44.491E. Here you can see a very tight fold in the rocks on the platform near the base of the cliff. The centre of the fold is so tight the toe or your shoes would just fit into it. This is a relatively small feature in the rocky shore and may be hard to find. OK to skip if too hard to find!

Beyond this point you can walk the coast line via the boardwalk or the rock platform. The boardwalk is easier but you will have to descend to the rocks below for each waypoint.

The third waypoint is at 37^o 48.239S 148^o 44.497E. Here you can see a piece of sandstone that appears to be floating in the finer grained rocks. Because of the extreme folding in these rocks and the way they are eroded small pinched-off bits and windows into folded bits can be often be seen. This is a relatively small feature in the rocky shore and may be hard to find.

The fourth waypoint is at 37^o 48.250S 148^o 44.509E. This location is a pebble beach. Here you can see well rounded examples of all the rock types from the local area. How many distinctly different types can you find? The rounding is the result of constant movement of the pebbles and boulders by waves. This action knocks them into each other and slowly wears them down. Sometimes they break and form more angular fragments and the process starts again.

The fifth waypoint is at 37^o 48.301S 148^o 44.575E. Here you can see an excellent example of a series of small ‘parasitic folds’ on the limb of a larger fold. The rocks in this area are full of folds at all scales, spend some time looking at how they influence the way the rocks erode. OK to skip, often buried under sand!

The sixth and final waypoint is at 37^o 48.361S 148^o 44.500E. The rocks here are distinctly different. This is a quartz diorite dyke. It was formed from magma intruding the sedimentary rocks and must be younger than them.

From this point you can return to Sailor’s Grave the same way you came or by the inland walk that starts a bit further along the beach. If you are feeling very adventurous you could continue on to Cape Conran proper where you will find West Cape.

To log your visit to this site you need to answer the following questions to GeoGeckoEd (through profile above):

a)What rock type forms the outcrop at Beware Reef?
b)What compass bearing is the strike of the rocks at the first waypoint?
c)What direction is the pointy end of the fold at the second waypoint pointing? This is an optional question because the fold may be hard to find.
d)What is the strike of the dyke at waypoint six?

Once verified, you can log your visit, but you must include the number of people in your group who visited this Earthcache. Pictures are welcome but no spoilers please!