VOLCANO, SUBMARINE MAGAMA, AA, PAHOEHOE, BASALTIC LAVA. BLOCK LAVA, PYROCLASTIC LAVA, LAVA FLOWS, ERUPTIONS, MAGAMA

WHAT EXACTLY IS LAVA?

Howdy ya’ll! Are you either staying warm in the northern hemisphere or cool in the southern hemisphere? I sure hope so. I’m not doing so bad myself…but I sure fall into bed in pure exhaustion every night! Some of it’s from overwhelming mental and/or physical drain and some of it is just from old age, lol! When I am overwhelmed mentally my brain just feels like mush. Does that ever happen to you too?

Speaking of mush, what happens when rock turns to mush? it becomes lava of course! Encyclopaedia Britanica defines lava as; “…magma (molten rock) emerging as a liquid onto the Earth’s surface. The term lava is also used for the solidified rock formed by the cooling of a molten lava flow. The temperatures of molten lava range from about 700 to 1,200 °C (1,300 to 2,200 °F). The material can be very fluid, flowing almost like syrup, or it can be extremely stiff, scarcely flowing at all. The higher the lava’s silica content, the higher its viscosity (resistance of flow).”¹

Did you know there are actually five different types of lava flows? Two have their names from the Hawaiian people; pahoehoe and aa (pronounced ah-ah). Pahoehoe flows have a smooth, gently undulating surface that resembles hummocks. “The liquid

lava flowing beneath a thin, still-plastic crust drags and wrinkles it into tapestry-like folds and rolls resembling twisted rope.”²

Aa lava flows, on the other hand, leave a surface that is extremely rough with partially loose, irregularly fragmented pieces (hence the name aa). Once hardened and cooled, this type of flow is very difficult, and dangerous, to hike over.

Block lava flows “resemble aa in having tops consisting largely of loose rubble, but the fragments are more regular in shape, most of them polygons with fairly smooth sides.”³

Basaltic lava flows can be of two different kinds. Thin basaltic flows “generally contain many holes, or vesicles, left by bubbles of gas frozen into the congealing liquid. Thick flows, which remain hot for long periods, may lose most of their gas before the lava congeals, and the resulting rock may be dense with few vesicles.”⁴

And lastly, pyroclastic flows (left and below right) are a fluid mixture of hot but solid fragments and hot gas and have a low viscosity. Therefore contrary to the other types of flows which move slowly, pyroclastic flows “move more like a dense, low-viscosity gas pouring down a slope and even move upslope if they have enough momentum; their downslope velocities often exceed 100 km (60 miles) per hour.”⁵

Volcanoes and vents where the lava first surfaces can be spectacular. They can occur on land or underwater (mainly in the ocean). Interestingly enough, submarine volcanos vents and fissures are estimated to account for 75% of the annual magma output. The vast majority of these submarine volcano’s are located near areas of tectonic plate movement that are known as ocean ridges. Most are found in the deepest parts of the oceans but some also exist in shallow water. When this is the case, magma can be spewed into the air during an eruption.

Since my novel takes place just one hundred and six years after the flood when plate tectonics were still under great motion, volcanoes and earthquakes were very prevalent. It would have been a trying time to live, especially with so few humans and only one city in the whole wide world.

I hope you think about volcanoes a little differently now…with the understanding that those erupting today are left over from a more violent time, a time that was a part of Gods’ judgment on the wickedness of mankind. And that you can see how much God loves us because even with wickedness abounding once more after the flood, He made a way to redeem us instead of ending the world for once and for all. And that redeemer is Jesus.

Until next week, God bless and take care!

Willow Dressel