Glacial erosion.mov
Summary
TLDREl guion del video explora cómo la erosión glaciar, mediante el abrasión y el arrancón, esculpe paisajes espectaculares. Se describen las áreas circulares llamadas 'cirs' en la cima de los glaciares, las paredes verticales conocidas como 'head walls', y cómo el hielo lleva sedimentos y produce estrías en la roca. Se contrastan las valles glaciares, con sus perfil U-shape, con los valles fluviales. Se explican fenómenos como los 'fjords', 'horns' y 'aretes', y se menciona el descubrimiento de John Muir sobre la formación de valles como el de Yosemite.
Takeaways
- 🧊 La erosión glaciar puede crear paisajes espectaculares, tanto por abrasión como por arrancar rocas.
- 🏔 Los círculos o 'Cirques' son áreas circulares en la parte superior de los glaciares donde la nieve se acumula y comienza a erosionar la roca.
- 🗻 Las paredes traseras de los círculos, conocidas como 'head walls', pueden ser muy empinadas debido a la erosión glaciar.
- ❄️ La erosión glaciar también puede llevarse rocas, transportándolas y depositándolas en otras áreas.
- 🗻 Los glaciares pueden erosionar rocas dejando marcas, como striaciones, que indican la dirección del flujo del hielo.
- 🏞 Las valles glaciares son fáciles de distinguir de los valles fluviales debido a su forma en U y paredes empinadas.
- 🌊 Las fiordos son bahías angostas y profundas que fueron erosionadas por glaciares y luego invadidas por el océano.
- 🏔 Los 'hornos' son montañas con lados muy empinados que quedan cuando los glaciares erosionan las laderas circundantes.
- 🏞 Los 'aretes' son crestas muy empinadas que quedan entre valles glaciares después de la erosión.
- 🏞 Las 'Paternoster lakes' son una serie de lagos en cadena que se forman en valles glaciares y se asemejan a un rosario.
Q & A
¿Qué son las formaciones de paisaje creadas por la erosión glaciar?
-Las formaciones de paisaje creadas por la erosión glaciar son el resultado de dos procesos principales: la abrasión glaciar y el arrancamiento. El hielo puede erosionar las rocas sobre las que se desplaza y también arrancar trozos de roca que luego transporta.
¿Qué es un 'Cirque' y cómo se forma?
-Un 'Cirque' es un área circular en la parte superior de un glaciar donde la nieve se acumula y comienza a erosionar la roca. Se forma por la acumulación de nieve y el arrancamiento de roca por parte del glaciar.
¿Qué es una 'Headwall' y cómo se relaciona con un Cirque?
-Una 'Headwall' es el muro muy empinado en la parte trasera de un Cirque. Se forma debido a la erosión intensa del glaciar, que provoca que la pared se rompe y se desmorone.
¿Qué es la abrasión glaciar y cómo afecta la roca?
-La abrasión glaciar es el proceso por el cual el hielo, al moverse sobre la roca, la desgasta y la raya, dejando marcas llamadas estrías. También puede pulir la roca, dejándola suave y lisa.
¿Qué son las 'Striations' y cómo se forman?
-Las 'Striations' son rayas y arañazos que dejan las rocas por la erosión glaciar. Indican la dirección en la que el hielo se movió sobre la roca.
¿Qué es un valle glaciar y cómo se diferencia de un valle fluvial?
-Un valle glaciar es un valle con una sección transversal en forma de U, formado por la erosión de un glaciar. Se diferencia de un valle fluvial, que suele tener una forma más amplia y en V, formado por la erosión de un río.
¿Qué son las 'Paternoster Lakes' y cómo se forman?
-Las 'Paternoster Lakes' son una serie de lagos en cadena que se forman en un valle glaciar. Se llaman así porque recuerdan un rosario, con lagos distribuidos de manera similar a las cuentas de un rosario.
¿Qué es un 'Horn' en el contexto de la erosión glaciar?
-Un 'Horn' es una montaña con lados muy empinados, formada cuando un glaciar rodea una montaña y la erosiona de manera que quedan lados muy陡峭 y una cima puntiaguda.
¿Qué es un 'Arete' y cómo se relaciona con los valles glaciares?
-Un 'Arete' es una cresta muy empinada y estrecha que se forma entre dos valles glaciares. Es el resultado de la erosión glaciar que ha sido más intensa en los valles que en la cresta.
¿Qué es un 'Fjord' y cómo se relaciona con la erosión glaciar?
-Un 'Fjord' es un estrecho y largo golfo o bahía que se forma cuando un glaciar se desplaza hacia el mar y luego se derrite, dejando atrás un valle inundado por el mar. Es una forma de paisaje que muestra la interacción entre la erosión glaciar y el mar.
Outlines
🏔️ Procesos de erosión glaciar
El párrafo 1 explica cómo el hielo de las glaciares puede erosionar el paisaje de manera espectacular, a través de dos procesos principales: la abrasión glaciar y el arranque. La abrasión es similar al proceso de erosion por el agua, pero más intenso, y el arranque se refiere a la acción de los glaciares al pluckar piezas de roca y transportarlas. Se describen las áreas circulares llamadas 'cirs' en la cima de los glaciares, donde el hielo acumula y comienza a erosionar la roca. También se menciona el 'head wall', una pared muy empinada en la parte trasera del 'cir', y cómo el hielo con sedimentos puede erosionar aún más. Se observan las 'striations' en la roca, que son rayas producidas por el paso del hielo, y cómo este puede pulir la roca hasta dejarla suave y brillante. Finalmente, se describen las características de las valles glaciares, que son distinguibles por su forma en U y paredes empinadas, en contraste con los valles fluviales.
🌊 Fjords y formaciones glaciares
El párrafo 2 explora cómo los glaciares pueden dar lugar a la formación de fiordos, que son senos de agua estrechos y profundos que se extienden desde la costa hacia la tierra. Se discute cómo, cuando un glaciar llega al océano, se desintegra en icebergs y cómo, en el pasado, los glaciares eran mucho más grandes, lo que indica que los fiordos estaban una vez llenos de hielo. Se menciona el cambio en el nivel del mar durante la era de hielo y cómo esto ha afectado la ubicación actual de los fiordos. Además, se describen otras formaciones glaciares como 'horns', que son montañas con lados muy empinados y afilados, y 'arêtes', que son crestas muy estrechas y agudas entre valles glaciares. Se relata la historia de John Muir y su contribución a la comprensión de la formación de Yosemite Valley por glaciares, y se mencionan estructuras como 'cirques', 'valleys', 'hanging valleys', 'glacial troughs' y 'Paternoster lakes', que son una serie de lagos en cadena en valles glaciares.
Mindmap
Keywords
💡Erosión glaciar
💡Cirque
💡Headwall
💡Arrancón
💡Abrasión
💡Striations
💡Valle glaciar
💡Lago de glaciar
💡Fjord
💡Horn
💡Arete
💡Piedmont glacier
Highlights
Glaciers can create spectacular landscapes through erosion.
Glacial erosion involves two main processes: abrasion and plucking.
Abrasion is the grinding away of rock by ice.
Plucking is the process of ice breaking off pieces of rock.
Cirques are circular areas at the top of a glacier where erosion begins.
Headwalls are steep walls at the back of a cirque.
Freezing and thawing can cause rockfalls into the cirque.
Striations are scratches on rock surfaces made by glacial movement.
Glaciers can polish rock surfaces, making them smooth.
Cirques can sometimes contain lakes known as cirque lakes or tarns.
Glacial valleys have a distinct U-shaped cross-section.
Glacial valleys are distinguished from river valleys by their steep sides and depth.
Misfit streams are small rivers flowing in valleys carved by glaciers.
Paternoster lakes are a series of lakes in glacial valleys, resembling a rosary.
Fjords are long, narrow bays carved by glaciers and now invaded by the ocean.
Glaciers were much larger during the last ice age, evidenced by polished rock surfaces.
Horns are sharp-edged mountains formed when a mountain is surrounded by cirques.
Aretes are steep ridges formed between glacial valleys.
Half Dome in Yosemite Valley is a famous example of a glacially formed landform.
The lecture concludes with a summary of the landscape features created by glacial erosion.
Transcripts
Landscapes formed by glacial erosion
like water ice can erode the landscape
and it does a fabulous job now don't get
me wrong water does a truly fine job too
but if you want spectacular scenery ask
some ice to do its work how does it work
two processes glacial abrasion and by
plucking like water it's capable of
grinding away the rock that it travels
over but also it can pluck away pieces
of rock and take it on their merry way
let's start at the top the top of the
glacier is a circular area called a uh
Circ that's where the snow has
accumulated and started to take away
some of the rock one way is by grabbing
the Rock and plucking it and carrying it
away bye there it's gone also by doing
so much erosion it will cause the back
of the cir to be very very steep that
steep wall is called a head wall and if
it's so steep it will start breaking
apart of course there's a lot of
freezing and thawing going on and pieces
of rock will fall down onto the Circ the
ice will carry it away and now that it
has all this sediment with it it can
start its second method of erosion
called abrasion here we have some stried
rock we know that ice has gone over this
rock you can see the scratches and even
tell the direction in which the ice
flowed okay I can't tell if it went that
way or this way but I know it didn't go
that way that would be just silly so all
of these scratches are called
striations it can even polish The Rock
smooth here are my lovely hiking boots
sitting on top smoothly polished Granite
the granite usually looks like that all
rough but the ice has traveled over this
spot up in the sieras polishing it as
smooth as can be let's take another look
at those cirs as I said they are
circular areas located at the top of a
glacier Valley where the ice begins
sometimes they'll have a Circ lake or a
Tarn in them after the snow is all gone
uh that little depression is a great
place to collect some
water here we have some cirs you can see
how very steep they are and here's a
lovely Circ in the sieras one of the
cirar
notice the valley shape totally
different from a river valley here we
have a very big u-shaped cross-section
of the Valley now a glacial Valley is
easily distinguished from a river valley
if you saw a valley like that you'd say
oh look that must have been a young
river that carved that Valley or a
valley like this broad you shaped Valley
you'd say oh look that must have been an
Old river that laid down a flood plane
and left us that Valley but if you saw a
glacial Valley you would go oh my that
is a valley look how steep the sides are
look how deep it is now it might have a
little river in the bottom but that
little tiny River didn't carve that
Valley that's a misfit stream a stream
that's flowing in a valley that was cut
Long Ago by
ice so here we have a nice broad
u-shaped glacial Valley you can see
they're mighty
pretty here's another
one and here's another one but instead
of just having one Lake a Circ lake at
the top it has a whole series of lakes
and they're strung together like a
series of beads somebody thought that
this series of beads reminded him of a
rosary which is a set of beads that
people use to say their prayers or
they're Our Father P nostr Lakes is the
name given to this series of lakes in
glacial valleys named for a rosary
here's a glacial Valley but it's hanging
high above the main glacial
trough that's because tributary valleys
like these deliver their ice to the top
of the main Glacier they don't carve all
the way down to meet the main glacial
Valley the way a river does so here we
have a tributary Valley joining the main
glacial
Valley the main glacial Valley is much
deeper so when the ice is gone this
tributary Valley is hanging high above
the original large of
Glacier that's what explains bridal veil
Falls in yede here we have the U-shaped
valley of the tributary Glacier hanging
above the much
larger yeus Valley with a beautiful
waterfall this is bridal veil Falls FS
FS are long skinny narrow Bays that were
carved out by glaciers but have since
been invaded by the ocean now wait a
minute when a glacier hits the ocean
what happens to it yes it breaks off
into icebergs so how is it we can have
the ocean in a glacial Valley that
doesn't make sense well let's get a few
Clues to figure this
out here we have the try arm Fjord in
Alaska and here are the two soyer
glaciers coming to join it but you can
see a line right here this red line has
above it rough Rock and below it
polished Rock what polished that rock
must have been ice that indicates that
these glaciers must have been much much
larger in the past and in fact they were
the past being last ice age added its
greatest about 11,000 years
ago I took that picture way up here in
the Fjord looking at the Sawyer
glaciers but this F continues all the
way down to the
ocean and there's evidence that ice
filled it up to the brim until it
reached the ocean where it finally caved
off into
icebergs since then all of these
glaciers have melted
well where did all that melt water go it
went into the ocean so during the Ice
Age the sea level was much lower and in
fact this would have been sea level but
since then sea level is now all the way
up this galaal
F here are some more fjords the fjords
of Iceland so every one of these Bays is
now at sea level but they were once
filled with
glaciers horns
when a mountain is surrounded by cirs it
ends up having very very steep sides and
can often be turned into a very
distinctive sharp edged mountain called
a horn this is not just a horn this is
the matter
Horn of course you may be a little more
familiar with a matter horn you can find
in
Disneyland arett aretes are very very
steep sided ridges that that are between
glacial valleys the glacial has eroded
steeply on each side of it leaving this
sharp Ridge
behind those of you who know your French
know that aett means stop and certainly
if you are hiking in this area and AET
would do an excellent job of stopping
you so let's see what you've learned
what is this structure it's called Tagan
Lake but it is of course a cir with a
lake in it or a cir
Lake this is Yus Valley this is the
glacial Valley and here's that little
hanging Valley coming into it now yeus
Valley was a mystery to those 150 years
ago Whitney thought it was the result of
a giant earthquake tearing the Earth
apart but it was John mure who had
traveled up in Alaska looked at those
glaciers and came back to his beloved
Yus Valley and decided that it was
formed by
glaciers he was of course right here's
another view of Yus Valley steep side so
steep that half of a granite Dome fell
into it leaving behind you guessed it
half doome if you've never heard of John
mu or half doome shame on you all you
have to do is take out a California
quarter and you'll find John M in Half
Dome of Yus Valley there for you to
admire what do we have here oh yeah
another
Circ and I don't know about you but I
see a
horn so let's see the yellow here what
do you think oh yeah hanging Valley
here's the main glacial Valley glacial
trough here we have a ridge between two
valleys that would be an ett here we
have a steep Mountain a horn
circular area at the top of a of a
glacial Valley that would be the Circ
and a series of lakes going
down those Lakes are Peter noter Lakes
so that's it you have learned the
landscape of glacial erosion we're done
I don't know about you but I'm now in
search of a snack bye
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