High Quality Content by WIKIPEDIA articles! The Wairere Boulders are an unusually large assemblage of basalt boulders in the Hokianga, in the far north of New Zealand. The boulder area, surrounded by subtropical rainforest, has been transformed into a park area to enable visitors to view this oddity of nature. It is the only valley worldwide which is formed by basalt boulders sitting on a clay base.The boulders in the Wairere valley are the erosional remnants of a lava flow out of lake Omapere (near Kaikohe) that has been dated as approximately 2.8 million years old. There are two dates for these, so called Horeke basalts: one at 2.84 and the other at 2.67 million years. There is a slight difference in chemistry in the two rocks that have been dated suggesting that the eruption took the form of several flows that once blanketed the high ground to the east of Horeke.