Science Infoblog

During your geology course you will have found that igneous rocks form large crystals when they are allowed to cool slowly and small crystals when they the cool fast. When a volcano spews lav out into the ocean volcanic glasses (obsidian) or special formations called pillo lavas can result.

Pillow lavas form when molten rock comes in contact with cold sea water. Toothpaste shaped tongues of lava are squeezed away from a large feeder tube. We can see this happening around Hawaii today. Kilauea burst into life about 500,000 years ago and has been pumping huge volumes of lava into the ocean ever since. There is evidence to suggest that similar activity was responsible for producing rock structures at Te Henga on Auckland’s west coast. The volcanic region that existed then must have matched the size of the Ruapehu massif which has been around for the last 250,000 years

If you head towards the southern end of Te Henga beach the rocky cliffs are mostly quite spectacular formations of pillow lavas. They originated in the same way Kilauea produces them now. They lie on top of slightly older volcanic conglomerate.

Now try the quiz if you are really bored and don’t have a life.

<a href=”http://www.mystudiyo.com/act69605/mini/go/te_henga_beach_rocks” mce_href=”http://www.mystudiyo.com/act69605/mini/go/te_henga_beach_rocks”>Te Henga beach rocks</a>