Green, Black, Red, and Pink Sand Beaches
From GeoClasses
Contents |
Abstract
Green, black, and red sand beaches are all created by the same formation and weathering processes. They are created by basaltic igneous rocks that have different element and mineral compositions. All three types of sand are formed initially by lava flow, so beaches that have black, green, and red sand are found near a volcano. On the other hand, pink sand beaches are formed very differently. They are not formed by lava rocks like the other three, but are formed by the skeletal remains of Forminifera, coral, and other shell organisms. They are found where coral reefs and Forminifera are plentiful. This site will provide information about these four types of beaches specifically, including: their life cycles, compositions, locations where these beaches can be found, and even some interesting facts about them.
Introduction
Green, black, and red sand beaches have a lot in common in the way that they share the same source of formation and all go through the same weathering processes that actually turns basaltic rocks into sand. Pink sand beaches have similar weathering processes as these three other sands, but their source is quite different. Though all four types of sand seem to have a lot in common, they are all quite individually spectacular and each have unique properties and characteristics.Through the information provided it is hoped you will begin to appreciate and marvel at these rare and beautiful landforms.
Green Sand Beaches
The Life Cycle of a Green Sand Beach
Green sand beaches are extremely rare and are formed by basaltic igneous volcanic rock which has plentiful amounts of olivine. These rocks made of olivine can be one of two types: either a rock entirely made of olivine called a dunite rock, or a gem-like rock called a peridot. The rocks weather over time creating small particles of olivine, silica, and other basalitic particles. The olivine weathers quickly into sand crystals because it is formed at high temperatures and is unstable at the Earth's surface. The other basaltic rocks also gradually weather into sand. The olivine crystals are much heavier than the other sand crystals so they remain on the beach when the other sand is washed away due to the strong waves. Because olivine is scarce in comparison to the other rocks that come from lava flow, green sand beaches are rare and typically relatively small, ranging from 50 to 100 feet in length.
Interesting Facts about the green sand of Hawaii:
The Hawaiians considered green sand to be the tears of the Goddess Pele and used the sand in healing ceremonies. Peridot is also the August birthstone and is used in jewelry as well as collected as a gemstone.
What Green Sand is Comprised of:
- Olivine
- Silicates
- Iron
- Magnesium
Green sand beaches are only found in regions that that are on the edge of a volcano and have high wave energy. They are found at the edges of volcanoes because there is an abundant source of mafic rock and must specifically contain plentiful amounts of olivine. Examples include:
- The Big Island of Hawaii
- Guam
Black Sand Beaches
Black sand beaches are made of basaltic rock which comes from the lava flowing into the water and solidifying. Waves from the ocean crash onto the shores and erode the basaltic rock, grinding them into coarse sand grains which create these black sand beaches. Black sand beaches have a short life span as a result of new lava flow covering the black sand, and the weathering process is started all over again.
Interesting Fact about Black Sand:
It used to be a myth that where there was black sand, there was gold. Black sand indicates that the area is rich in minerals, including gold. The myth has been disproven because it does not happen most of the time. However, there is still a large correlation between the two- where one is found, the other is likely to be found as well. Coincidental? It is still unknown, but it has led quite a few people on wild goose chases!
What Black Sand is Comprised of:
- Iron rich mafic minerals
- Basalt
- Gabbro
- Magnetite
- Silica
- Traces of metal such as:
- Thorium
- Titanium
- Tungsten
- Zirconium
- Traces of gemstones such as:
- Garnet
- Topaz
- Ruby
- Sapphire
- Diamond
Locations of Black Sand Beaches:
Generally black sand beaches can be found in regions that have constant lava flow combined with high wave energy. They are found at the edges of volcanoes where there is an abundant source of mafic rock and a scarcity of silica.
Some Examples Include:
- The Big Island of Hawaii
- Maui, Hawaii
- Newdicks Beach of New Zealand
- Auckland, New Zealand
- Patagonia, Chile
- Gorda, California
- Tiarei, Tahiti
- Taveuni, Fiji
- Castle Bruce Bay and Batalie in the Dominican Republic
- Santorini, Greece
Red Sand Beaches
The Life Cycle of a Red Sand Beach:
Red sand beaches are very rare. Because they are so rare, isolated, and difficult to get to, not much is known about them. It is known that the sand forms primarily from eroded volcanic cinder cones. Cinder is a pyroclastic igneous rock that is very similar to pumice. The cinder cones, which are very vibrantly red, erode into beautiful red sand beaches.
What Red Sand is Comprised of:
- Mostly Iron (and Hematite)
- Mafic minerals
- Basalt rock
Locations of Red Sand Beaches:
Red sand beaches also must be near a volcano, specifically ones that have cinder cones. They typically exist in bays or inlets where the waves cannot erode the sand away. They actually are still growing because of the repetitious deposition of the cinder and the minimal erosion of the sand.
Some Examples Include:
- Red Sand Pocket Beach, Maui, Hawaii
- Santorini, Greece
- Matala, Crete
Pink Sand Beaches
The Life Cycle of a Pink Sand Beach
The pink sand beaches are the most unique out of all the beaches because they are not formed from volcanic rocks. They are actually formed by the accumulation and deposition of the remains of calcium carbonate shells, and skeletons of invertebrates such as corals, clams, forams and other shells. These beaches begin with a tiny animal called a Forminifera, which has red pigmentation. The Forminifera live in the coral reefs that are close to the shore. When these highly pigmented Forminifera die, their skeletons fall to the ocean floor. The water then bleaches out some of the pigmentation turning them into a pinkish hue. They weather and erode because of the waves and become a part of the sand that eventually creates these pink sand beaches.
What Pink Sand is Comprised of:
- Eroded skeletons of Forminifera
- Calcium Carbonate
- Skeletons of corals and other shells
Locations of Pink Sand Beaches:
Pink sand beaches are exceptionally rare because they are only found in two places in the world- the islands of Bermuda and in Scotland. These two places contain enough forams, Forminifera, and coral that when these organisms die they actually tint the sand a visible pink.
Some Examples Include:
- Only in Bermuda and Scotland
Naomi Henderson: My Personal Experience
I have been to Hawaii and have seen both a green sand beach and a black sand beach. The black sand beaches were commonly found throughout the islands, and you could actually tell where the black lava rocks were weathering into sand. The rocks were fragile and crumbled extremely easily, reinforcing what we have learned about these igneous rocks being unstable at the Earth's surface. These huge lava rocks are actually home to many different types of animals due to tide pools that are in the cracks that fill up with the ocean water when the tide comes in. Sea cucumbers, star fish, crabs, sea urchins, and many different kinds of fish could all be seen within the pools. These animals were not the only organisms who took advantage of these lava rocks, we also all appreciated them because they attract the sun's rays better, which gave us a better tan! I have also been to the Green Sand beach in Hawaii, and it was quite a journey to get there! It was approximately a 13 mile round trip hike to get to see such a rare beauty. To get there you have to walk over land and lava rocks, which also adds to the difficulty of reaching this beach. Once you get there though it is worth all the effort. The green sand beach is in an inlet that has a beautiful curved shape. The walls of the inlet that you hide to climb down to get to the beach were extremely steep and felt dangerous. It took us about fifteen minutes to just get to the beach from the top of the inlet. When we got to the actual beach and got to see the sand, we were amazed. The green sand is one of the most beautiful naturally occuring substance I have ever seen. It is a combination of green sand and gemstones that glitter in your palm. The hike back to our car seemed to not last as long because all we could talk about was what we had just seen. I would definitely recommend seeing this beach some point in your life!
Conclusion
When one imagines a beach usually only the common white or tan sand beaches come to mind. However, it is now evident that there are at least four uniquely colored rare sand beaches that are scattered throughout the Earth. Alluring black sand, dazzling green sand, vibrant red sand, and exquisite pink sand can now be imagined as some of the most extraordinary, breathtaking beaches in the world. Thank you for exploring the world of gorgeous multicolored beaches.
References
Anderson, Genny. (2003). Hawaii Geology, Plate Tectonics/Hot Spot. Retrieved June 28, 2007, from Marine Science. Website:http://www.biosbcc.net/ocean/marinesci/02ocean/hwgeo.htm
Fitzhugh, Rod. (2002). Black Sand. Retrieved June 28, 2007, from Arizona Gold Prospectors. Website:http://arizonagoldprospectors.com/blacksand.htm
Forbes, Keith A. (2007). Bermuda's Beaches. Retrieved June 28, 2007, from Bermuda Online. Website:http://www.bermuda-online.org/beaches.htm
Microbus. (2007). Sand Anaylsis. Retrieved June 27, 2007. Website:http://www.microscope-microscope.org/applications/sand/microscopic-sand.htm
The Basalt Beach. Retrieved June 27, 2007. Website:http://www.albion.edu/geology/Geo210_Hawaii/MaunaLoa/Black%20Sand%20Beach.htm
U.S. Geological Society. (2004). Black Sand. Retrieved June 27, 2007, from Coastal Geology of the Parks. Website:http://geology.wr.usgs.gov/parks/coast/sand/blacksand.html
U.S. Geological Society. (2004). Green Sand. Retrieved June 27, 2007, from Coastal Geology of the Parks. Website:http://geology.wr.usgs.gov/parks/coast/sand/blacksand.html
