In December a large group of North East Field Nats traversed the Fanny Bay Conservation Area – a narrow 7 kilometre coastal strip extending from Tam O’Shanter Bay at Lulworth to Weymouth.

The terrain included sandy and shingle beaches, rocky shore platforms backed by tall dunes and dense fringing shrubberies where locals have carved out walking tracks.

The leader of the outing was Jason Orr, himself one of those locals.

The dark rock along the coastal strip is basalt, an igneous rock formed from lava that welled up and flowed over the older Mathinna Group Sediments about 300 million years ago.

Click a photo for a great view

Hexagonal columnar jointing is evident, caused by contractions within the cooling lava. Much of this seaside basalt has a lumpy appearance due to erosion within the joints caused by pressure from salt crystals formed within evaporating sea swash.

Erosion of a different kind was obvious with some beaches that are usually sandy being denuded of sand in the seasonal storms and cliffs falling into the sea with high tides.

Vegetation, severely pruned by salt-laden winds, included coastal saltbush, coast daisy bush, sea box and the sprawling bower spinach – an edible plant.

Less exposed shrubbery along the bush tracks included paperbark, coastal dogwoods, drooping sheoaks, boobyalla [myoporum] – not to be confused with coastal wattle.

This was a fairly long walk compared to our usual, but after two of our recent outings having to be cancelled, there was quite a social aspect to the day, especially at the end of the walk.  Jason had access to the equipment at the Lulworth Community Picnic Pavillion where we barbequed and chatted, in awe at how well stocked it was. A big thank-you to Jason for leading an excellent outing.

There was quite a deal of interest in the geology of the area and it was agreed by all that we could easily visit the area again and concentrate our study in a smaller area.

Mike Douglas