welcome back guys to the northwest

geology guy my name is Scott your

amateur geologist and now I get to do

this video all over again

YouTube wouldn't let me do more than

four seconds and cut it off so I

apologize to any of you guys that got

the notification came over to look for

it and found it nothing but my past

videos but okay well let's do it all

over again if it's going to be even

better the second time but we're gonna

be talking about lava tubes and how

they're formed lava tubes are created by

channel of lava like the Hawaiian last

the Hawaiian Kilauea eruption and it

created a like a river of lava and it

starts to crust over but let's take a

look at the lava Channel okay here's a

lava channel from Kilauea last eruption

and as you can see down here downstream

where I guess it's upstream it's

starting to crust over and and even down

there along here and if it stays flowing

long enough it'll start to cool on top

and all of this will become crusted over

and then we'll thicken them with time

because lava cools from the outside in

so this will seal the whole channel with

a thin crust is it and then they get

thicker and then the hot lava underneath

will continue to flow down strip

downstream until it hits water like in

Hawaii or hit a valley and just dump it

out down downhill but lava tubes don't

happen at every volcano

now I remember as a kid taking the field

trip from school all the way down to

what they call the eight cave from Mount

st. Helens it's right next to Mount

Saint Helens and that was very

interesting it was a very deep and very


kinda out of place in the Cascades to

have a lava tube but it was very neat it

was almost like it had like a boring

machine down there that just bored out a

long tube but incredibly dark down there

you have to have I think they recommend

three different light sources in case of

failure a hardhat very good

hiking shoes because of the rough

terrain but I was just odd that we're

walking in the hole that's Oh like 33

feet high and I think the highest point

was 88 feet to me that's just a heck of

a lot of lava flowing through there to

keep it going but normally speaking you

need basaltic lava the very thin runny

lava Hawaiian type lava that's only

about 45 percent silica and silica is

formed in every lava flow no matter what

type of lava it is it or silicon in all

of it the Hawaiian type basaltic lavas

average around forty-five percent silica

and the more viscous type lavas like

Endocyte die site and rhyolite they're

all around the 72 to 75 percent mark

which makes it very thick and viscous

like trying to pour peanut butter you

know the like Adams peanut butter that

you have to stir the oil into it it

comes out very slow even though it's

still very hot but it's very thick

almost like if you ever seen anybody do

glassblowing on TV it's red hot but it's

very viscous and and doesn't run right

off the pole and that's why I'm really

wondering why we had such a large lava

tube coming out of st. Helens which is

known to have the more viscous type

lavas but that's something that I maybe

will try to research little further and

give you guys an update

find out why they had a large basaltic

flow I know we I did one of my first

reports was about about do we have a

volcano in Oregon Portland Oregon and

the boring lava field is all about

Celtic flow in an area that shouldn't

have been basalt it should have been a

higher silica content lava like rye

light or die site but it's just very

interesting how this happens but

sometimes on rare occasions a lava tube

can be formed from a long fissure

vertical I mean it sorry horizontal

Vischer under underground and the lava

will find a way into that go through it

plug up and cracks like that and just

keep it going until it breaks out

downstream more and I can't remember the

name of it but it's over in Iceland you

know the volcano will be over here on

the left but the lava breaks out way

down flank from the volcano travels

through a tube in a fissure and comes

out breaks up downstream work said whoa

wait a minute weird this come from but

this is the most common way a lava tube

is formed I know there's two three maybe

four lava tubes on Big Island but I mean

I only know a tune I can't pronounce one

of them but thurston lava tube is in the

volcano national parks area and you can

walk down and walk through it safely but

if you ever do happen to go in a lava

tube like that just remember don't touch

the walls don't write on the walls

because it has its own ecosystem with

what they call cave slime and different

organisms are

there and they strongly discourage

anybody from even touching the walls so

I hope you found this interesting and if

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well everyone take care and I'll see you

on the next video