Gibberagong Track is an out-and-back 12km 3 hour training walk, with a nice climb to get your heart rate up at the end. The walk starts from the end of Grosvenor Rd, Wahroonga, and heads first along the fire trail, then narrows into a path to descend the big hill and cross Lovers Jump creek. The path follows Cockle Creek down the valley to Bobbin Head. Return the same way.
The rocky area near the signposted aboriginal axe grooves at the intersection close to Bobbin Head make a nice tea stop. There is an interesting engraving of a man wearing a curious skirt on the other side of the path near the axe grooves. A short marked side track leads to a small patch of rain forest .
Depending on your pace and time constraints, turn around at the axe grooves, or if you are walking faster, continue on the boardwalk through mangroves and saltmarsh to cross the bridge to reach Bobbin Head itself.
Gibberagong is the alternate name for Cockle Creek, and means “place of rocks”. There is no shortage of rocks in the creek as you follow it down, until it widens and becomes tidal. In the 19th century, aboriginal middens were mined in this valley, burnt to produce lime and shipped to Sydney for making mortar. Cockle Creek joins Cowan Creek and ultimately flows into the Hawkesbury.
Wildwalks has detailed track notes on the Gibberagong Track.