Browns Field Walk, Wahroonga – Flora of a Diatreme

Images: courtesy Conroy, R.J. Martyn J.E, Mitchell P.B., Robinson A.M. et al. (2022) The Natural and Cultural History of the Ku-ring-gai Geo-Region, New South Wales. Proceedings of the Linnean Society of New South Wales 144, 129-226. https://openjournals.library.sydney.edu.au/LIN/article/view/17009

Leading off Campbell Drive a proposed geo-trail leads to accessible geo-sites around Browns Field, the cleared parkland in the centre of the Fox Valley diatreme. A diatreme is a cylindrical volcanic vent and typically filled with broken fragments of volcanic rock and shattered rocks from the walls of the vent.

Geologist Dr John Martyn will lead this walk and point out the geological features of weathered outcrops, the diatreme’s contact zone with Hawkesbury Sandstone and its vegetation. This walk is the second event in the FOKE Ku-ring-gai Geo-region series that AABR is pleased to support.

Browns Field’s deep, fertile, clay-loam soils support the warm temperate rainforest, even some young red cedar. Along the creek, there’s a bank of moss and mixed shrubs and nearby a miniature forest of juvenile sassafras (Doryphora sassafras).

The rainforest on the Cooper Crescent outcrop is rich and diverse, in part the result of experimental plantings over decades. Consequently, for this botanical region there are some very uncommon species, “exotic natives”, such as the giant stinging tree (Dendrocnide excelsa), blue quandong (Elaeocarpus grandis), and mature river oak (Casuarina cunninghamiana), corkwood (Endiandra sieberi), pencil cedar (Polyscias murrayi).

RSVP to Attend

Date:

Sunday 23 April, 2023

Time:

Meet at 9:45am for a 10am start, finishing at 12noon

Meeting point:

Entrance to Browns Field next to 97A Campbell Drive (opposite Boyne Place) Wahroonga (off Fox Valley Rd)

Getting there:

No easy public transport. For carpooling, please contact Chloë to offer lifts from a railway station or let her know that you’d like a lift – a day beforehand!

Caution: check track work on this Sunday: https://transportnsw.info/alerts#/metro-train

By car, turn off Fox Valley Road.

What to bring:

Please wear good walking shoes, bring a bottle of water, snack, sun protection and insect repellent. No dogs permitted. If unwell, stay home and rest.