EarthCache @ Maui's Blowhole
By the way the 5 rating on Terrain is if you go down to the blowhole :)
You do not have to go to the blowhole to log this cache
Now according to Wikipedia, the free encyclopedia
In geology, a blowhole is formed as caves grow landwards and upwards into vertical shafts and expose themselves towards the surface , which can result in quite spectacular blasts of water from the top of the blowhole if the geometry of the cave and blowhole and state of the weather are appropriate. The Kiama Blowhole (Kiama, New South Wales, Australia) is believed to be the world's largest blowhole.
Lava tubes are natural conduits through which lava travels beneath the surface of a lava flow, expelled by a volcano during an eruption. They can be actively draining lava from a source, or can be extinct, meaning the lava flow has ceased and the rock has cooled and left a long, cave-like channel.
Lava tubes are formed when an active low-viscosity lava flow develops a continuous and hard crust, which thickens and forms a roof above the still-flowing lava stream. Tubes form in one of two ways: by the crusting over of lava channels, and from pahoehoe flows where the lava is moving under the surface.
Lava usually leaves the point of eruption in channels. These channels tend to stay very hot as their surroundings cool. This means they slowly develop walls around them as the surrounding lava cools and/or as the channel melts its way deeper. These channels can get deep enough to crust over, forming an insulating tube that keeps the lava molten and serves as a conduit for the flowing lava. These types of lava tubes tend to be closer to the lava eruption point.
Further away from the eruption point, lava can flow in an unchanneled, fanlike manner as it leaves its source, which is usually another lava tube leading back to the eruption point. Called pahoehoe flows, these areas of surface-moving lava cool, forming either a smooth or rough, ropy surface. The lava continues to flow this way until it begins to block its source. At this point, the subsurface lava is still hot enough to break out at a point, and from this point the lava begins as a new "source". Lava flows from the previous source to this breakout point as the surrounding lava of the pahoehoe flow cools. This forms an underground channel that becomes a lava tube.
A broad lava-flow field often consists of a main lava tube and a series of smaller tubes that supply lava to the front of one or more separate flows. When the supply of lava stops at the end of an eruption or lava is diverted elsewhere, lava in the tube system drains down slope and leaves partially empty cave-like conduits beneath the ground.
Such drained tubes commonly exhibit step marks on their walls that mark the various depths at which the lava flowed, known as flow ledges or flow lines depending on how prominently they protrude from the walls. Lava tubes generally have pahoehoe floors, although this may often be covered in breakdown from the ceiling. A variety of speleothems may be found in lava tubes including a variety of stalactite forms generally known as lavacicles, which can be of the splash, shark tooth, or tubular variety. Lavacicles are the most common of lava tube speleothems. Drip stalagmites may form under tubular lava stalactites, and the latter may grade into a form known as a tubular lava helictite. A runner is a bead of lava that extrudes from a small opening and then runs down a wall. Lava tubes may also contain mineral deposits that most commonly take the form of crusts or small crystals, and less commonly, as stalactites and stalagmites.
Now from my personal observations and what I have Read
The Blowholes on Maui are formed by the volcanoes. This happens when lava flows into the ocean via Lava Tubes. Now Lava tubes are formed when the Lava flows and the outer crust hardens and forms a hollow tub that continues to flow lava. The lava stops flowing but is still hot enough inside the tubes to remain liquid and slowly continues to flow out leaving the hollow tube.
Now As time passes some where along the line the tube itself ruptures leaving a whole on its top side. Elsewhere along the tube at waters edge erosion collapse, allowing the waves to crash into the opening. As the water from the tides rush in pushing to its limits. Finding the Opening and gushing forth in a large beautiful spray mixture of water and air, rushing 100s of feet into the air.
Now Mother Nature has formed all of the necessary elements to a perfect Blowhole.
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Your Final Logging Requirements for the, Earth Cache @ Maui's Blowhole
1. You Must take your picture with the Blowhole in the background and post it at the time of your log
2. Estimate how high the blowhole water streams into the air.
3. For great measure add at least one more picture of your trip.. Please describe why it was so special...
4. Now you must enjoy the rest of your time on the island.
For more information about earth caches click here
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This one is easy it is in the open :) Can't you see it?