Renowned author and geologist Dr John Martyn will lead this walk and explain why Bicentennial Park at West Pymble is a GeoRegion site.

Bicentennial Park's old abandoned quarry face is the site of a basalt dyke. It is an excellent example of the thermal effects of super-hot intruded basalt magma on Hawkesbury Sandstone, which has been visibly baked and recrystallised to a hard, white quartzite, once sought after and quarried for heavy duty tasks like road base and railway ballast.

Dr John Martyn is author of the books Sydney’s Natural World, Field Guide to the Bushland of the Lane Cove Valley and Rocks and Trees, all published by STEP. He’s also co-ordinator and compiler of STEP’s published series of bushwalking maps.

Meet at: Entrance to West Pymble Bicentennial Park via Bicentennial car park (entrance via Loftberg Road

Cost: Free

Bring: Water, snack and wear good walking shoes

Enquires: Janine Kitson, Vice-President, Friends of Ku-ring-gai Environment (FOKE), 0428 860 623