I found a book about NZ geology in the mobile library this week. Flicking through it yesterday afternoon I recognised a photo of distinctive limestone rocks at Waro, about 25kms from here. I've glimpsed the amazing rock formations as I've driven past on SH1 (through the little settlement of Hikurangi just north of Whangarei) and always thought it would be cool to stop and check them out.
So I drove over there and parked in the reserve next to the little lake created by flooding an old limestone quarry. The most popular features of the reserve are not the rocks- which are buried in scrub, nor the lake, which is clear enough to identify all the kinds of rubbish on its floor though this doesn't seem to deter a diversity of water fowl enjoying it. Almost everyone I saw there on the drizzly grey afternoon were using the transfer station (nice asset for any public park) and the skateboard bowl (with matching grafitti to that seen on some of the nearby rocks).
The limestone is amazing, carved by rain into smooth curving channels, massive slabs balanced on narrow columns, faces the texture of fish scales. Which is appropriate as the rock was created as ooze from microscopic sea creatures accumulated under a warm shallow sea covering most of what is now Northland during the Oligocene. As continental plates collided the sea bed buckled and lifted and "great slabs of ocean-floor sediments rose up and slid on the soft ooze".
After my walk I drove up to Ngawha Springs for a soak in hot, cinnabar flavoured water: my book says that basalts deposited mercury in its sulphide form. Which sounds bad and smells bad, but oooooh it feels sooooo gooooood....