What type of lava is rough and chunky

In the times where we have to cross an a'a flow which does happen, to get to the best places we try to find the least area to cross to minimize any possible injury. If you have gloves and need to cross a'a, you might consider wearing them, if you're not already.

Another form of lava is officially named Pele's Hair. This is a wonderful form of lava, and most unexpected. It is also one of the few lava forms that you can create yourself though nature produces some of the best examples. Pele's hair looks like long strands of greenish-gold hair. In bright sunlight it is a shimmering gold color, perfectly straight and as thin as human hair.

The lengths can be anywhere from particle sized to several feet long, though most Pele's hair that you will encounter unless it is brand spanking new will be in the 2 to 6 inch length.

Pele's hair is created when molten lava is ejected into the air - as happens when lava fountains or enters the ocean and explodes. If the airborne molten lava is small enough, and the wind is strong enough, the wind will pull the lava droplet and turn it into a hair-sized piece of rock.

It is as if the wind extruded "rock wire" from the liquid mass, much as wire is created in a factory. You can find Pele's hair all over the place, but mostly near vents, skylights and the ocean entry. Crevices in the ground or areas where rocks form a corner are locations where the blown Pele's hair can collect. Be careful though, Pele's hair while only the size of human hair it is like glass fiber and is very sharp.

It is easy to get a small piece stuck in your hand while you are examining it, if you are not careful. Gloves can be useful in this situation. You can create your own Pele's hair by trying to take a sample of pahoehoe flow.

When you dip a kitchen whisk, or other implement, into an active pahoehoe flow, as you extract the sample - if you do so quick enough, strands of hair will extrude from your sample back to the ground.

These may be many feet in length but only as thin as human hair. These fragile strands do not last long, but show you exactly how they are created. Pele's tears are another form of lava related loosely to Pele's hair.

Just as with Pele's hair, Pele's tears start out being small molten bits of lava sent hurtling into the air due to an explosion or, more often, lava fountain. By the time the tears hit the earth they have fully cooled and retain their oval or tear shape.

There are many places within the Hawai'i Volcanoes National Park where there are literally acres of Pele's tears. Quite a bit is right along the roadway and it is fun to park and go look for Pele's tears. Because the tears are the result of fountaining fissures, anywhere there was a fissure that fountained you can find the tears downwind. Lava bombs can be thought of as Pele's tears taken to an extremely level. Formed the same way; lava bombs are HUGE blobs of molten lava ejected high into the air.

As these blobs fall to earth they rotate and gravity converts them into round and oval rocks that hit the earth already cooled.

These are huge rocks, ranging from several feet in diameter to the size of cars, and while you might be able to escape a fountain of Pele's tears, you would never escape a fountain of raining lava bombs.

Lava bombs can be found all over the Big Island. There are many fine examples within the Hawai'i Volcanoes National Park but some of the best examples can be found on the road up to the Mauna Loa Weather Observatory off Saddle Road, as well as the upper road around Mauna Kea 4-wheel only. On Mauna Kea there are huge fields hundreds of acres where there are perfect lava bombs every 3 to 5 feet - spaced as if planted - an amazing site to behold.

Where else can you go and find Green Sand Beaches - other than Hawai'i probably a few places, but not many. Actually, Hawai'i has many different colors of sand. Black, gray, brown and green sand beaches are from lava of various compositions, whereas pink and white sand beaches are from coral. Green sand comes from the semi-precious gemstone peridot, a form of olivine. Occasionally a flow will be very rich in olivine crystals and the rocks produced by this flow will have a distinctive greenish hue.

Jagged : something that has sharp pieces or sharp points sticking out of it. Rubbled : material that has been ground up into smaller pieces. Rubbly : a rubbled texture on the surface of a lava flow. Surface roughness : the texture of a surface. Volcanic vent : an opening of a volcano or a rift beneath a magma chamber.

The explosive power of a volcano is a wonder to witness from a safe distance , and shows how scary, yet beautiful, nature can be. Great plumes of smoke and ash rise into the air, covering the land in darkness. From its vent, a molten, glowing red-orange material rises from the Earth.

Beautiful fire fountains and streams black and orange pour across the land. What is this material? When it erupts and flows on the surface, it is known as lava. When lava flows, it creates interesting and sometimes chaotic textures on its surface. These textures let us learn a bit about the lava.

Try to think of these lava flows in the way you might imagine different thick liquids moving across a surface. Take ketchup and thick syrup, for example. Ketchup is thick, but not sticky, so as more is added, it moves easily and lumps will even out to make a smooth surface. A thick syrup moves slower, and is stickier, so as more is poured out, it might fold on top of itself.

These different types of movements can help us classify different lava flows. A classic, smooth lava flow is like ketchup, while a rough lava flow is more like a thick or drying syrup. A classic lava flow with a smooth surface and curved ripples and folds is known as pahoehoe. Pahoehoe is the name of both the lava type and of the whole lava flow. Pahoehoe lava flows are formed from eruptions that are not very violent, but that slowly extrude lava. This tells us something about what the lava flow is made of and how easily it flowed over the surface.

Pahoehoe lava flows cover kilometers of land and are typically only a couple of meters thick. To cover a distance that great, the lava would have to flow with little resistance and stay at high temperatures to keep moving.

Now we have seen a smooth surface lava flow, but what about a rough one? Because of its flow speed, the lava flow surface is disrupted and torn into pieces. If you want to understand how the material on the surface is disrupted, imagine stretching taffy. The formation process of basaltic ropy pahoehoe lava. Light-colored mound in the foreground is composed of pumiceous lapilli. Picture taken in Tenerife, Canary Islands.

Aa lava is a rough rubbly crust of a lava flow. It is a major lava flow type. Other important subaerial lava flow types are pahoehoe and blocky lava. Aa and pahoehoe are terms that were brought to geological terminology from the Hawaiian language. Aa is according to native Hawaiians a sound one makes if he or she tries to walk barefoot on such a lava flow. Walking on it is very slow and potentially dangerous even if one has good hiking boots. It is such a miserable experience because the uppermost part of aa lava is composed of loose clinkery unstable blocks.

You can never be sure that the rocks you are stepping on do not move. They often do. This means that ground beneath your feet is unstable and you may easily lose balance. It is no good if that happens because the edges of fresh aa lava rubble may be very sharp. Sometimes aa lava blocks are so big that one has to climb over them.

It makes moving progress very slow and bare hands will get scratched for sure. One thing that in my opinion is often poorly understood is the fact that aa and pahoehoe are terms that only describe the upper part of a lava flow. It is more correct to say that aa lava is a type of lava flow crust, not lava flow itself. Both aa lava and pahoehoe are usually massive beneath the crust which may be smooth pahoehoe or rubbly aa.

Massive part usually contains vesicles gas bubbles which will fill with secondary minerals like zeolites in older lava flows. This process takes considerable time and requires low-temperature hydrothermal alteration. There are no amygdules vesicle filling mineral masses in historic lava flows.

Aa lava is more common than pahoehoe. Special conditions are needed for pahoehoe to form: lava with low viscosity high temperature, low silica content , low effusion rate, and gentle slope. Aa lava is free of such restrictions and therefore forms instead of pahoehoe if the conditions are not right. It is usually the speed of advancing lava flow that determines whether aa or pahoehoe forms and that depends on the effusion rate and steepness of the slope.

Once aa lava is formed it never reverts back to smooth pahoehoe form. Here you can see both smooth pahoehoe and irregular aa lava types. This beautiful cascade of lava in Hawaii is largely composed of pahoehoe type lava flow, but in the left-hand side some lava tongues have broken to form aa instead of pahoehoe. Pahoehoe lava flow in the center that have partially covered the aa-type flow in Hawaii. Lava flow formed in on La Palma in the foreground. It is almost completely aa lava.

Pahoehoe forms only small part of it. Aa lava in the foreground near the western coast of La Palma, Canary Islands. This lava flow formed during the eruption of Cumbre Vieja in Here is a nice exposure near the southern tip of La Palma which shows the internal structure of aa lava. Here are two lava flows. Lower part of the flow is massive lava which has a rubbly surface.

And on top of it is another aa lava flow. And here is whole mountainside in La Palma composed of many such lava flows. The interior of a lava flow may be columnar because of thermal contraction. However, really beautiful regularly shaped columns like these form usually in a stationary well insulated lava lake not in an actively moving lava flow. Blocky flows are common if the silica content of lavas is higher composition of basaltic andesite to rhyolite 5. Blocky lava flows resemble aa lavas.

They also have highly irregular surfaces covered with debris, but they contain larger lava blocks with smoother sides and angular edges with common dimensions from few decimeters to several meters.

Blocky flows grow higher as they advance and may reach more than meters in height 3. Here is a blocky flow formed in from La Palma, Canary Islands. Blocks are angular and have much smoother sides than separate pieces of aa lava.

Blocky flows may be tens of meters high. Nea Kameni island in the caldera of Santorini, Greece. Andesitic blocks. Nea Kameni, Santorini. Pillow lava is usually basaltic or andesitic in composition and always associated with water.

Each pillow is like a bag that has quickly chilled margin which is filled with molten material. Pillow lavas are usually associated with mid-ocean ridge volcanism. The upper part of the oceanic crust is composed of countless number of lava pillows, but they can also form in much shallower conditions, even in lakes or under glacial ice. Some sources do not even mention pillow lava as a type of lava flow 1.