Any Earth science enthusiasts here (particularly volcanoes)?

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I am a space enthusiast and part of my interest translates to geophysics. Speaking of Venus, that planet has no water to act as lubricant for plate tectonics so the entire crust is rigid in a state known as stagnant lid, ie the entire crust is one big plate. Earth releases much of its heat through the process of plate tectonics, Venus is nearly the same size as earth so it has to dispose of about the same amount of heat. It has plenty of hot spot volcanoes but those are not as nearly efficient as mid ocean ridges and cannot dispel of most of the heat. So heat builds up underneath the crust until it cannot handle it anymore and the entire crust melts in a dramatic resurfacing event. The last time this happened was 200 million years ago, as that is how old the entire planets crust is.

Wow, that's absolutely fascinating! Thank you for sharing. (:

I'm about to graduate as a geologist, after a semester of electives to fill out my degree.
So here's some of my favourite bits from volcano science:
There are 2 basic types of magma :
: felsic (feldspar, quartz rich, tends to be lighter in colour, found in the crust, makes granites and has thick magma of high viscosity) These are your candidates for gassy explosive pyroclastic type volcanoes.

:Mafic (rich in iron, magnesium, darker in colour low viscosity, so runny consistency, make basalt which is sea floor) These make your runny, flowy less dangerous volcanoes which is what Hawaii is made of.

Inside the mantle is more iron and magnesium rich, which is ultramafic.

So the how the volcano behaves depends heavily on magma composition as well as on the area through which the magma is coming up.

I know this bores a lot of people. I actually find it hard to fathom that anyone can be bored by this.

A real rock nerd

Who reckons yellowstone is going to blow? I mean in our lifetimes. It's definitely going to blow soon, but geologically speaking, 'soon' covers a lot of human lifetimes.

I think geology rocks.

Stay with your science. It is well grounded and people who understand what is going on below become boulder and boulder.

ruveyn

"never heard that one"

I think there are at least 2 clips on youtube where some rock nerds made up a song called that.

I saw on someone's hoodie "geologists - we're gneiss, tuff and wacke"
I'd agree with that

Took introductory geology in the seventies- happened to be at the time of the plate tectonic revolution in geolgical thinking.

I remember that stuff about lava (dont recall the terms mafic, and felsic, but that was the idea) The continents are made of light colored light wieght rock. And the sea beds of dark heavier basalt. The explosive volcanoes on land are made of granite lava. The result is the tall "strato volcanoes" (like Mt. Fuji, Mt. Shasta) that look like regular big snow capped majestic mountains (like the Matterhorn, or Pikes Peak) but with holes in the top.

Basaltic lava causes you to have gentler erupting "shield volcanoes" that you find in the pacific islands like Hawaii.

There is also a lava type called "Andesite" which is intermediate between those two.

But anyway -the shield volcanoes only get six percent as tall as they get wide (so they look like shields laid on the ground rather than like majestic mountains when viewed from the side).

The biggest mountain in the entire Solar System is olympus mons on Mars. Which is a basaltic shield volcano much like those that formed Hawaii. At 79 thousand feet it is several times as tall as Mount Everest, but it takes up an area the size of the state of Missouri because that altitude is only six percent the width of its base (the same ratio as shield volcanoes on earth) so as big as it is- it wouldnt make a very good postcard if photographed from the ground ( but then neither would the island of Hawaii if you drained away the sea around it and photographed it).

But they dont seem to have stratovolcanoes on Mars, nor Venus either.

Felsic = FELdspar + Silicon
Mafic - MAgnesium + Ferric

Don't know when the terms were coined.

Stratovolcanos are layered and the compositions of the layers can be variable. Variation comes partly from tectonics. For example plates going down into the mantle take seafloor sediment, water and other stuff with them. But there is a lot they don't know about how magma differentiates.
You can actually ID the location on Earth from the composition of the magma, it is that distinctive. Crust is enriched in certain trace elements, and Mantle is enriched in others (I am talking about gold, uranium, platinum, nickel, everything)
There is a lot to magma science. Isotopes play an important part figuring it out. It is used to sleuth out the history of the earth, the interior composition, as well as try to figure out where to find certain resources.

If other planets had stratovolcanoes, it would say a lot about their past, especially if they could samples to analyze.

Can't believe I never heard this one


I do remember some young fellows on a second year field trip laughing and saying things that involved massive granitic intrusions and girls.
In my opinion they were giggling.