yo geolooggggyyyyyyy (lots of good brain food I promise)
There is a wonderful diverse world of volcanic eruptions! One thing you might not have thought about is how glaciers often form at the top of large cone volcanoes and the way the lava erupting interacts with a large volume of ice can shape the eruption significantly. One of the biggest results are lahars, like muddy, liquidy avalanches but even faster and deadlier.
To give you a good point of reference though, one thing that links all volcanic eruptions and is a good axis for comparison between different eruptions and volcanoes is that all magma pretty much comes up from the interior of the earth to the near surface starting at the same chemical composition (called “mafic” it sounds like “basic”). Mafic minerals are heavy, dense and tend to be dark colored when viewed in a hand specimen, a common mafic rock is Basalt. Most of the oceanic crust is basalt.
Available Wherever You Get Your Bottoms Of Oceans
Felsic minerals tend to be light both in mass and in coloring, a comon felsic rock is Granite.
Looks like your mom’s countertop, I remember it well how perfectly the skin of her naked legs complemented the gorgeously polished crystal textures of quartz, potassium feldspar (K-feldspar), sodic plagioclase feldspar, hornblende amphibole, and mica
This is a graph of Viscosity, the more Viscous the Magma the less ability it has to flow like a liquid (and thus the more likely a plug is likely to form inside a volcano). It is also more difficult for lower temperature magma to flow, and Felsic lava is almost always lower temperature (cooling had to occur to become Felsic in the first place so).
Here is something to ground these two ends of what probably seems like an arbitrary spectrum to focus on, the Oceanic Crust (i.e. the bottom of the ocean) on this planet is overwhelmingly made up of mafic rocks (i.e. Basalt) and large amounts of felsic rocks only really form on continental plates where there is the space and depth of rock to house massive chambers of magma, especially since Oceanic Plates are always getting subducted and recycled unlike Continental Plates (and thus the magma might be subducted & recycled before it could even begin the process of becoming significantly felsic). This axis of chemistry is critical to Geologists because it points directly to some of the biggest trends of geology on the planet and a related fact I might as well drop here is that because of these dynamics Continental Plates (i.e. basically the continents) can be orders of magnitude older (on the order of 1 billion years or older, the earth is only 4 or so billion years old) than oceanic crust which tends to be younger than 200 million years old (and often is much younger).
On Continental Plates if magma feeds into large underground chambers (batholiths) and is allowed to cool slowly then certain minerals will begin to form and precipitate out like snow that layers up on the bottom of the chamber. The specifics of what minerals these are depends on how long, how hot, how much pressure and other factors but you can vaguely think of it as a process of distillation where magma progresses from the original “mafic” composition to a “felsic” one as the high temperature mafic minerals crystallize out leaving behind a progressively more felsic magma mixture. The felsic minerals don’t crystallize out until the magma has significantly cooled and thus if the magma chamber undergoing this process is integrated into an eruption, it can become extremely explosive and destructive.
Half Dome in Yosemite California is such a trip because it is so clearly what we imagine in geology when we talk about a really big underground chamber of magma (after it has cooled into rock obv), Half Dome just looks like exactly how you would imagine it if you dug up an old magma chamber and cracked in half with a suitably large hammer
yo geolooggggyyyyyyy (lots of good brain food I promise)
There is a wonderful diverse world of volcanic eruptions! One thing you might not have thought about is how glaciers often form at the top of large cone volcanoes and the way the lava erupting interacts with a large volume of ice can shape the eruption significantly. One of the biggest results are lahars, like muddy, liquidy avalanches but even faster and deadlier.
https://www.usgs.gov/media/images/d-claw-computer-simulation-landslide-begins-mount-rainiers-west-flank-tahoma-glacier
https://www.usgs.gov/programs/VHP/lahars-move-rapidly-down-valleys-rivers-concrete
To give you a good point of reference though, one thing that links all volcanic eruptions and is a good axis for comparison between different eruptions and volcanoes is that all magma pretty much comes up from the interior of the earth to the near surface starting at the same chemical composition (called “mafic” it sounds like “basic”). Mafic minerals are heavy, dense and tend to be dark colored when viewed in a hand specimen, a common mafic rock is Basalt. Most of the oceanic crust is basalt.
Available Wherever You Get Your Bottoms Of Oceans
Felsic minerals tend to be light both in mass and in coloring, a comon felsic rock is Granite.
Looks like your mom’s countertop, I remember it well how perfectly the skin of her naked legs complemented the gorgeously polished crystal textures of quartz, potassium feldspar (K-feldspar), sodic plagioclase feldspar, hornblende amphibole, and mica
This is a graph of Viscosity, the more Viscous the Magma the less ability it has to flow like a liquid (and thus the more likely a plug is likely to form inside a volcano). It is also more difficult for lower temperature magma to flow, and Felsic lava is almost always lower temperature (cooling had to occur to become Felsic in the first place so).
https://en.wikipedia.org/wiki/Magma
Here is something to ground these two ends of what probably seems like an arbitrary spectrum to focus on, the Oceanic Crust (i.e. the bottom of the ocean) on this planet is overwhelmingly made up of mafic rocks (i.e. Basalt) and large amounts of felsic rocks only really form on continental plates where there is the space and depth of rock to house massive chambers of magma, especially since Oceanic Plates are always getting subducted and recycled unlike Continental Plates (and thus the magma might be subducted & recycled before it could even begin the process of becoming significantly felsic). This axis of chemistry is critical to Geologists because it points directly to some of the biggest trends of geology on the planet and a related fact I might as well drop here is that because of these dynamics Continental Plates (i.e. basically the continents) can be orders of magnitude older (on the order of 1 billion years or older, the earth is only 4 or so billion years old) than oceanic crust which tends to be younger than 200 million years old (and often is much younger).
On Continental Plates if magma feeds into large underground chambers (batholiths) and is allowed to cool slowly then certain minerals will begin to form and precipitate out like snow that layers up on the bottom of the chamber. The specifics of what minerals these are depends on how long, how hot, how much pressure and other factors but you can vaguely think of it as a process of distillation where magma progresses from the original “mafic” composition to a “felsic” one as the high temperature mafic minerals crystallize out leaving behind a progressively more felsic magma mixture. The felsic minerals don’t crystallize out until the magma has significantly cooled and thus if the magma chamber undergoing this process is integrated into an eruption, it can become extremely explosive and destructive.
https://opentextbc.ca/geology/chapter/4-2-magma-composition-and-eruption-style/
Half Dome in Yosemite California is such a trip because it is so clearly what we imagine in geology when we talk about a really big underground chamber of magma (after it has cooled into rock obv), Half Dome just looks like exactly how you would imagine it if you dug up an old magma chamber and cracked in half with a suitably large hammer
Huh, interesting. I didn’t expect to learn about volcanoes today but here I am! Thank you for the explanation