SAMOAN 'FLOWERPOT' - an enigma. EarthCache
SAMOAN 'FLOWERPOT' - an enigma.
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IS THIS A VOLCANIC PLUG or a SEASTACK?
Fatu or Flowerpot Rock is a natural landmark, and just offshore off one of the islands of American Samoa. It is located near the entrance of Pago Pago Harbour, close to the town of Fatumafuti.
The coordinates take you to a PUBLIC SCENIC LOOKOUT on the sea side of the road.
American Samoa is situated in the South Pacific ocean on the Pacific Plate, the largest of the world’s tectonic plates, It is a group of islands that lie about halfway between Hawaii and New Zealand and about 100km east of the island country of Samoa, which is part of the same archipelago, ethnicity and culture. It is an unincorporated territory of the United States.
The main city is Pago Pago, but the smaller town Fagatogo is the constitutionally designated seat of government. The governor’s office is located in the village of Utulei, located on the opposite side of Fagatogo from Pago Pago
Fatu ma Futi or Flowerpot Rock , is an islet at the western side of the entrance to Pago Pago Harbour. It is located out in the ocean and is is home to exotic birds and fruit bats.
The Samoan chain consists of high volcanic islands, atolls, and submerged reef banks near the southwest margin of the Pacific plate. The islands are bigger towards the west, with some active volcanic action in particular at Savai’i and Upolu.
The chain is unusual, particularly when compared with the Hawaiian chain, because the islands are volcanically active on both the eastern and western ends of the chain, the islands are larger westward, the eastern most edifice is an atoll not an active seamount, and the chain consists dominantly of alkali rather than basaltic rocks which contain less sodium. While geological studies of the Samoan group are limited, the existing results are consistent with a hot spot
Although the island you stand on, Tutuila, is comparatively YOUNG, only 1.5 million years old, it has already submerged faster than the reefs can grow, leaving former barrier reefs as submerged offshore banks.
These banks are covered by diverse communities of living corals, but the reef formation was slower than sea level rise. There once was a series of larger islands which have subsided leaving the peaks and highest places exposed above the sea giving way to a ‘seamount chain
The island is sinking very slowly and headlands that jut outward into an open body of water such as an ocean leave the land formations unprotected against years of wind and wave erosion.
Fatu looks like a sea stack, a natural geological formation usually found near rugged coastlines and appearing as vertical stone columns offshore from a main land mass. The taller the sea stack, the more unstable it is. Eventually the sea stack will topple and make a stump. BUT it may be that it has survived a wave battering because it is much harder than the surrounding rocks? This is after all a volcanic region.
MAYBE the Flowerpot is a volcanic plug?
A volcanic plug also called a lava neck, is a volcanic landform created when magma hardens within a vent on an active volcano, and then the surrounding rock is ERODED away.
The appearance will be similar, in the sea, to a stack, that is, a geological landform consisting of a steep and often vertical column or columns of rock in the sea near a coast, isolated by EROSION.
EROSION -The impact of the waves and weather
Regardless of its geological origin, Fatu was exposed, over time by wind and water, processes of coastal geomorphology. It formed when part of a headland was eroded by hydraulic action, which is the force of the sea or water crashing against the rock.
As the water smashes up against the headland rock, the erosion process begins. Waves chisel away at the rock and over time a cave is formed. Wind is another factor of the erosion process that forms sea stacks. Both wind and water pound heavily on the rock pieces to crack and weaken the stone.
Waves continue to smash into the crack forming an ever enlarging cave over many years, breaking pieces of rock away slowly. Cracks and weak places are created due to the amount of intense hydraulic force with which the waves batter into the cave, especially during storms and swells.
Eventually, the cave will give way and the water will drill its way on through the back of the cave, thus creating an arch over the open section. The arch may survive the destructive forces of the waves for awhile, but eventually it will collapse away to reveal a large column of rock. This is the sea stack.
Once the sea stack is formed, the waves continue to smash into it. Eventually, over time, this stack will break away, throwing pieces of rock into the sea. The piece that remains is known as a stump.
LOGGING REQUIREMENTS
THIS IS NOT A "SAIL- BY" ON CRUISE SHIP CACHE . IF YOU DONT GO TO THE COORDINATES, THEN YOU CANNOT JUSTIFY LOGGING.
Visit the site! Message your responses, log your find. I will contact you ASAP. PLEASE don't include any answers in your log.
NO NEED TO WADE OR SWIM !!
(1) Could Fatu be a volcanic plug? Is there any thing you can SEE to help you decide? (Rather than internet research) .
SUGGESTIONS TO HELP WITH YOUR DECISION
----- Try to view in context not in isolation
----- USE the information in the text and think of the timeframe
-----Look at the rock you stand on near / on the beach. Does it appear the same type, are the bedding planes the same etc., as Fatu?
-----If yes, then it likely that is a seastack and part of the general geology
-----If no and the rock looks different, the beds not clear or different? Has it has survived because it much harder or less cracked than the rocks on the beach? Then it possibly is a plug of rock which extruded through existing rocks at a different time
(2) Describe the rocks close to where you stand. How resistant do you think they be over time?
(3) To validate your LAND BASED visit YOU MUST post a photo of you or a personal item with the 'FLOWERPOT' in the background, (ie ON LAND - not on deck. To prove you actually visited)
INDIVIDUAL RESPONSES ARE REQUIRED. GROUP RESPONSES WON’T BE ACCEPTED
ACKNOWLEDGEMENTS
Wikipedia -General Information on American Samoa
Landforms/eu -Information on volcanic plugs
TES - Information on Coastal Erosion
BBC - Information on Coastal Erosion
Additional Hints
(Decrypt)
Fgnaq pybfr gb gur ohf fgbc (CHOYVP NERN)
Ab cubgb = ab ybt!
Treasures
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