Welcome to the Bird Rock Earth Cache
I hope you enjoy this beautiful location and geology.
Bird Rock is located about 10kms from the main town along Walkerville South Road.
Bird Rock is a series of jagged limestone and shale bluffs, sea stacks, rocks and reefs that extend 1 km seaward from Walkerville. Tucked in on either side of Bird Rock are two small beaches. The northern beach is well protected from large swell. The beach on the southern side faces south-east and is more exposed. Both beaches are accessible on foot from Walkerville, via the rocks at low tide, or along a bluff-top walking track which is where this adventure will take you.
Please note this cache will be very difficult to do at high tide and is not recommended.
This is a significant location and was worked extensively for the Melbourne trade in the last two decades of the nineteenth century with a limestone kiln further down the beach. The geological structure changes at this location from the surrounding area with a complicated series of four distinct limestone formations.
The area is rich in history and has many other sites to see including the jetty, tramway, quarry, cemetery archaeological remains of the township and 6 kilns. In the 1850s a ship named SS Waratah captained by William Bell, became disabled with a damaged rudder while rounding Wilson's Promontory on its way between Sydney and Melbourne, and sought shelter in the bay and reported it to be a good, safe anchorage; thus giving the name Waratah Bay.
Studies in the area age this limestone from the Devonian Period which occurred from 416 million to 358 million years ago.
Limestone is a sedimentary rock, composed mainly of skeletal fragments of marine organisms such as coral, forams and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate.
About 10% of sedimentary rocks are limestones. The solubility of limestone in water and weak acid solutions leads to karst landscapes, in which water erodes the limestone over thousands to millions of years. Most cave systems are through limestone bedrock.
Today you will be exploring the rocks for answers to the Earth Cache
Questions
The posted co-ords will have you staring at a 'cave' like entrance.
Q1 Describe the surrounding rock in colour and texture at the entrance to the 'cave'. and can you spot any skeletal fragments of coral, forams or molluscs?
Walk through the cave and move around to the left (picture on cache page will be what you will see) and look to your left. You will see a different color vein in the rock.
Q2 What colour do you see in the vein here and how does it differ to the surrounding rock. Does it look out of place to you?
WP2 will have you climbing a little to give you a great view. There is a faint pathway to the top (about a 6m climb up). You will need to go back past the cave entrance. Do not climb from inside the cave.
Q3 Does the rock here look different on top of the sea stack to what is in the 'cave'. Explain the differences.
WP3 will have you at the bottom of the stairs.
Q4 Are the rocks here at the bottom of the stairs the same or different to what you have seen at bird rock?
Once you complete the EarthCache requirements you can post your find without delay, as per the EarthCache guidelines. You will also need to verify your find by sending me a message and provide your answers to the questions.
For a link to my profile, click here - Na'wal
Thanks for visiting this Earth Cache. I hope you enjoy exploring the area.
Feel free to attach photos to your log (optional) but please don't post any spoliers.
References ~ heritage council of victoria