a. During a week-long trip to the Big Island of Hawaii, EPS concentrators were able to study different types of sand (and enjoy the waves as well). Students visited black sand beaches like Punalu’u, Waipi'o Valley, and Polulu; and the white sand beaches of Spencer Beach and Mau’umae Beach. Hawaii also hosts a green sand beach composed of olivine crystals derived from basaltic lava rocks.
b. 360 Video: 35—Punalu’u Black Sand Beach The island of Hawaii was built up from the ocean floor by mostly basaltic lava flows. Basalt is a dark black rock, which is weathered and deposited as black sand beaches. Basalt has low silica content, so there are no white silica sand beaches in Hawaii (like most of those you’d find on the coast of the continent). Instead, white sand in Hawaii is derived from bits of coral reefs. Punalu’u is also known for the sea turtles (honu) often seen on the beach.
c. 360 Video: 85; 360 Photo 84—Polulu Valley Beach Like Punalu’u, the Polulu Valley beach is composed of weathered bits of basaltic rock. The Polulu Valley, however, is on the very wet eastern side of the island, where increased rates of erosion have formed the steep valley walls that surround the beach.
Figure 1: EPS students stroll along the Punalu’u Black Sand beach on the south side of Hawaii
Figure 2: Leore Lavin, Matt Luongo, and Maya Chung enjoy multiple angles of the Polulu Valley black sand beach
Figure 3: EPS concentrators pose for a group shot at Spencer Beach Park during the 2016 undergraduate field trip to Hawaii.
Hawaii also hosts a green sand beach composed of olivine crystals derived from basaltic lava rocks. b. 360 Video: 35—Punalu'u Black Sand
Black Sand
Black sand is sand that is black in color. One type of black sand is a heavy, glossy, partly magnetic mixture of usually fine sands containing minerals such as magnetite, found as part of a placer deposit. Another type of black sand, found on beaches near a volcano, consists of tiny fragments of basalt.
Beach The island of Hawaii was built up from the ocean floor by mostly basaltic lava flows. Basalt is a dark black rock, which is weathered and deposited as black sand beaches.
Sand coloration depends on the parent rock from which the beach sediments have eroded. The parent material may be from a local source (eroded from a nearby bluff or cliff) or may be transported long distances; for example, Mississippi River delta sediments may be transported from Montana.
In areas with volcanoes, sand comes from volcanic rock. This explains the colored beaches of the Hawaiian Islands. Red beaches come from volcanic rock that's rich in iron. Green beaches have lots of the mineral olivine.
Because Hawaii does not have a continental source of quartz sand like mainland beaches, the 'white' beaches and marine sediments here in the islands are primarily composed of the carbonate shells and skeletons of marine organisms, such as corals, algae, molluscs, foraminifera, echinoderms, and bryozoans.
Basalt is a dark black rock, which is weathered and deposited as black sand beaches. Basalt has low silica content, so there are no white silica sand beaches in Hawaii (like most of those you'd find on the coast of the continent). Instead, white sand in Hawaii is derived from bits of coral reefs.
Black sand comes from eroded volcanic material such as lava, basalt rocks, and other dark-colored rocks and minerals, and is typically found on beaches near volcanic activity. Black-sand beaches are common in Hawaii, the Canary Islands, and the Aleutians.
The beach itself was created approximately 49,000 years ago when a cinder cone (Pu'u Mahana) was formed during an eruption of the Mauna Loa volcano. Green Sand Beach is the unique combination of olivine-rich lava deposits and other sand components.
Similar to black sand, red sand is also composed of lava rock. Rather than spill into the ocean, this lava cooled above the water as part of the island. Exposed to open air, the high iron content of the rock causes it to form iron oxide, also known as rust. This is the same reason for Hawaii's infamous red dirt.
Green sand is the rarest color of sand in the entire world. It's caused by a special type of volcanic eruption in which olivine crystals (which are green) are brought to the surface of the earth.
Removing them can possibly upset the natural balance of each location they are removed from. In addition, it is illegal to take sand, dead coral, or coral rubble statewide per Hawai'i Revised Statute (HRS) §171-58.5 and §205A-44.
You CANNOT drive your rental car (or your owned car, or any other vehicle) to the Papakolea green sand beach in Hawaii. The hike to the green sand beach is NOT six miles. It is only two and a half miles and is relatively easy to follow due to all of the traffic in and out of the area.
These minerals can come from erosion of nearby landscape, volcanic eruptions, and even the grounding up of sea shells over decades, so the color and content of sand reflect the makeup of the surrounding landscape and even the beach's inhabitants.
Relaxation and natural beauty are the top draws. Known for its active volcanoes, wildlife refuges, and tall active peaks, it's little wonder that 88% of our respondents cite natural beauty as a reason for visiting Hawaii. Relaxing by the beach is the second most popular reason for visiting.
Because of constant volcanic activity, you'll find white sands and black sands on the island of Hawaiʻi. Located on the southeastern Kaʻū coast, Punaluʻu Black Sand Beach is one of the most famous black sand beaches in Hawaiʻi.
Like a filter, this leaves behind colors in the blue part of the light spectrum for us to see. The ocean may also take on green, red, or other hues as light bounces off of floating sediments and particles in the water. Most of the ocean, however, is completely dark.
Along certain coasts, finer particles like sand and silt can add to the water's murkiness since they're easily agitated and stay afloat for long periods. On the other hand, the sediments off clearer coasts may be heavier and coarser.
Phytoplankton, a microscopic plant-like organism, also produces chlorophyll which absorbs red and blue light causing the then remaining dominant color, green, to be the most pronounced. Nasa stated in an article, “the more phytoplankton in the water, the greener it is…the less phytoplankton, the bluer it is.”
Sediment plays a big factor in water color. Smaller, more fine sand particles can make water murkier since they are easily agitated. In clear water, sediments may be coarser and tougher to stir up since they are heavier and made of shell pieces and dead coral chunks.
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Figure 1: EPS students stroll along the Punalu’u Black Sand beach on the south side of Hawaii
Figure 2: Leore Lavin, Matt Luongo, and Maya Chung enjoy multiple angles of the Polulu Valley black sand beach
Figure 3: EPS concentrators pose for a group shot at Spencer Beach Park during the 2016 undergraduate field trip to Hawaii.
Figure 4: EPS concentrators make their mark on the Polulu Valley black sand beach.
