Mauna Ulu Trail (Lava Boredom Warning!)

Mauna Ulu stands for “Growing Mountain” which seems to be generally the case with volcanoes.  In 1969 a large fissure opened up in the forest and in 3 hours widened to a crack over a mile long.  Lava exploded in fountains up to 1771 feet high for a period of almost 5 years.

One of the features of the Mauna Ulu trail is that of lava trees.  Lava trees are formed when lava rolls up against a tree trunk and cools rapidly because of the wet wood.  More lava flows around it and builds up to form a cone which is hollow inside as a result of the tree eventually burning up.

Once lava cools into volcanic rock, it becomes known by 1 of 2 names.

Pahoehoe lava is smooth, folded or ropey, and is formed when lava cools more slowly.

A’a lava is formed when the flow is slightly cooler, loses sufficient gas, crystallizes or is sticky.  The molten rock loses elasticity and fractures instead of stretching.

This trail provided a marvelous contrast between pahoehoe and a’a.

One of the other features of the trail was the colour of the sand.  By looking closely you could see little green crystals called olivine (or peridot) which crystallized out separately.

At the end of the trail, we climbed a little forested hill called Pu’u Huluhulu, or shaggy hill, which was a 500 year old volcanic cone missed by the Maunu Ulu’s lava flows.  The vegetation was rainforest, and there was a step little crater at top.

We got a good viewpoint of Mauna Ulu, which was quietly steaming on top.  It is a subtle reminder that these volcanoes are not dormant--they are just not erupting at the moment.

One of the most fascinating things is how lava is revegetated over time.  Algae, ferns, ohi’a trees, lichens and mosses move in in that order.  The tenacity of plants is amazing.

We took a little side trip to a petroglyph site, which had miraculously escaped more recent flows.  The Hawaiian language was not written; natives ended up carving petroglyphs into the basalt which must have been a real chore, since basalt is very hard.

This little park had over 23,000 petroglyphs, of which over 16,000 were holes (perhaps 2" in diameter) where Hawaiians placed the umbilical cords of their newborns to give them a long and fruitful life.  Weird, eh?