Page 426 - Hawaii: Diving, Surfing, Pearl Harbor, Volcanoes and More

he Hawaiian-Emperor Seamount dis- ll of the Hawaiian Islands began over island has been beautifully carved and cul-
T plays the results of at least 70 million A the same hotspot before the Pacific tivated by wind and rain into the spectacu-
years of active volcanism, evolution and tectonic plate carried them to where they lar garden paradise of today.
migration. Specifically, the formation of Ha- lie today. They all began as huge moun-
waiian Island archipelago began, beginning tains like the Big Island, but over the eons awaiian volcanoes primarily erupt a
with the northwestern most island, the Kure wind, rain and subsidence make them ever H type of rock known as basalt. When
Atoll, approximately 28 million years ago, smaller. Often, a huge section of the island molten, basalt produces liquids of relatively
by way of the Pacific tectonic plate gradual- will cleave and slide back to the sea leaving high fluidity, compared to volcanoes that
ly moving northwestward at a rate of about that side of the island a long and towering erupt more silica rich magma types such as
32 miles per million years, or approximately cliff-line as is found today on the island of andesite, dacite or rhyolite. The fluidity of
3 to 4 inches per year, over a hotspot in the Molokai. The wind and rain carve beautiful molten basalt favors the formation of lava
Earth’s mantle. Currently, the Big Island of valleys that meander to the heart of the is- flows, which is why the Hawaiian volcanoes
Hawaii is over this hotspot and is the only lands. The mountains themselves are laced generally have gentle sloping sides. By
Hawaiian island, which has an active vol- with faults and lava tubes filled with water contrast, lavas with higher silica content are
cano where flowing lava, can almost always adding to island water reservoirs. The rain, more viscous and commonly produce either
be observed. This island rises 18,000 feet condensed from the air via the orographic thicker, shorter lava flows, thick blocky
before it breaks sea level and continues an- lifting of the trade winds by the mountain deposits and/or thick beds of ash that fall
other 14,000 feet above it. Viewed from the slopes, continually replenishes these reser- from the sky following explosive eruptions.
perspective of the sea floor this mountain is voirs. These other types of volcanoes (common
the tallest in the world at 32,000 feet. All of outside of Hawaii) are typically steeper
the Hawaiian Islands put together make up auai is the northernmost Hawaiian sided. Currently there are 3 Hawai’ian volca-
only half the landmass of the Big Island. K island but it was once located where noes that we can easily classify as active.
the Big Island of Hawaii lies today. During
these millions of years of tectonic drift the