The Lawrence Rocks are a group of two rocky islets, 6.8 ha and 1.5 ha in area, with an associated reef, 2.4 km south-east of Point Danger in western Victoria, Australia, and about 6 km south-east of the city of Portland.
It is also the only mainland Gannet Rookery found in Australia which is located on the tip of Point Danger. Once Lawrence Rocks is full, the overflow of Gannets sit at the tip of Point Danger.
Lawrence Rocks is part of a group that formed from the remnants of an extinct volcano, with the islets composed of basalt and tuff. The bay itself is actually a field of volcanic cones and craters now submerged by the sea. The islets were sighted by Lieutenant James Grant on 5 December 1800 from the survey brig HMS Lady Nelson and named for Captain Effingham Lawrence, one of the Elder Brethren of Trinity House.
Cape Nelson, Yellow Rock and Lawrence Rocks are from large basalt flows which have formed the base of the Cape and the Island, which are both capped by wind-blown sands now hardened into limestone sheets.
Tuff
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is compacted into a solid rock in a process called consolidation. Tuff is sometimes called tufa, particularly when used as construction material, although tufa also refers to a quite different rock. Rock that contains greater than 50% tuff is considered tuffaceous.
Tuff is a relatively soft rock, so it has been used for construction since ancient times. Since it is common in Italy the Romans used it often for construction. The Rapa Nui people used it to make most of the moai statues in Easter Island.
Tuff can be classified as either sedimentary or igneous rocks. They are usually studied in the context of igneous petrology, although they are sometimes described using sedimentological terms.
Questions
Q1 Viewing Lawrence Rock in the distance, describe the colours and what you see.
Q2 Explain what you think has happened on the right hand side of Lawrence Rock?
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References ~ greatsouthwestwalk.com, wikipedia & geology.com