The Whites - Pre Glaciation

[dr_wu002]

Appalachian Mountains

the Whites were thought to have rivaled the Himalayas, since the orogeny that created each is similar. The instructor said that the Whites were formed the last time the continents all bashed together. They formed a land mass that's today called Pangaea. Likewise, the Himalayan mountains are forming as the result of two different plates with land masses on the edges being forced together (Australian-Iandian Plate being forced northward into the Eurasian plate), which is how the Whites would've been formed.

Another thing too we should consider is that The Whites are part of a larger Mountain Chain -- The Appalachian Mountains. I assume that during the existence of Pangaea, the entire Appalachian Mountain Chain was large & high. Now, what has happened to the Whites is somewhat different than what happened to say, The Blue Ridge Mountains -- less glaciation and whatnot (at least recently, I believe) but still, they are roughly the same elevation. Any insight anyone?

-Dr. Wu

 

[diehard]

glaciation in the wHITES

An interesting question…something a geo-morphologist, or Geo-Forensic specialist (is
there such a person) would probably be able to reconstruct.

Many of the rocks of the White Mountains are only 150 +/- 25 million years old. These are the young ones, which we all scramble across when we are in the Pemi, in the Moats, Baldface, or the Percys. Now, when we are in the Presidentials the rocks are a bit older, at around 400, give or take, million years old. (The European Alps are around 25 (?) million years old). The last period of glaciation, perhaps 13,000 – 15,000 years ago. There is a lot of geologic history which has gone on in these mountains.

I’ve often wondered how many periods of glaciation have there been in 400 MY? One certainly wouldn’t say they would have ceased during the emplacement of the White Mountain Magma Series (Conway Granite etc), as volcanoes are known to exits under glaciers, today. What are the mechanics of a moving sheet of ice, over a mile thick?

I believe, a good geo-morphologist, could look at the present day structure, the skeleton of what is left, and like a Geo-Forensic specialist, reconstruct what this area looked like 150 or 400 MY ago….but what do I know…………

Jim Cahoon

 

[dr_wu002]

Many of the rocks of the White Mountains are only 150 +/- 25 million years old. These are the young ones, which we all scramble across when we are in the Pemi, in the Moats, Baldface, or the Percys. Now, when we are in the Presidentials the rocks are a bit older, at around 400, give or take, million years old. (The European Alps are around 25 (?) million years old). The last period of glaciation, perhaps 13,000 – 15,000 years ago. There is a lot of geologic history which has gone on in these mountains.

Like I said -- the time frame here kills me. 150,000,000 years vs. 400,000,000 years. A lot of thing can happen between in the 250,000,000 years in between. I find things that happen that incredibly slow difficult to imagine for some reason. It's almost like Geology is to the Earth as John Cage is to Music.

-Dr. Wu

 

[TDawg]

Time Scale

This link may help in putting geologic time into perspective. I go to school for this type of stuff and geologic time is kind of a pain in the ass. But here is is....http://www.ucmp.berkeley.edu/help/timeform.html

My professor gave this link to my White Mountain Region and Landform Ananlysis classes as an aid. You can click on the epochs to see what was going on at that time in geologic history and evolution.

Also prior to the Mesozoic Era the Whites were under an ocean and as the continents collided to form Pangea, the sediments laid down by rivers at the bottom of the ocean and formed into rock, were thrust upward and rose above the sea around 250 mya. maybe. The "Littleton Formation" is what NH predominatly rests upon and the rocks in the Presidentails are of the Littleton Formation. These were ocean sediments that formed into rock under pressure and thrust upward. The top of Mount Washington is the upper part of the formation (mica schist and quartzite) and other parts of the Presies are the lower part of the formation (gneiss). These rocks are metamorphic due to the intense heat and pressure that resulted from the continents colliding.

Anyways, I'm not much of a geologist either but I know a few things from my classes at Plymouth State. But that time scale site helped me make sense of it all so it might be of some worth to you folks as well.

Oh and by the way, I'm fairly new to this site, but it is growing on me like a fungus.

 

[Sundog]

Well, Dr. Wu, I can tell you a little about the history of the New England and the Whites. It all started with Laurentia, or Proto North America. It was the core from which North America as we know it grew. Around 450 million years ago a chain of island arcs collided with Laurentia in an event known as the Taconic orogeny. Prior to this orogeny, the edge of Laurentia was the Hudson river valley. The Taconic island arcs were accreted onto the Laurentian land mass as part of the continental slap subducted. Next came the collision with the Avalon terrane. Avalonia collided with Baltica (which later became part of northern Europe) and Laurentia about the same time. This event was known at the Acadian orogeny, and involved subduction of dense basalt from Avalonia to subduct under Laurentia. Such subduction was responsible for volcanism on the continent (think of the Cascades on the west coast resulting from the subduction of the Pacific plate under North America). Also, sediments from the Iapetus Ocean were scraped off and accreted onto Laurentia, along with arc volcanics and metamorphics from Avalon. This orogeny started roughly 425 million years ago. The terranes Laurentia, Avalonia, Baltica and later Siberia formed the land mass termed Euroamerica, which collided with Gondwana about 350 million years ago (I'll have to check my dates on this one) in an event called the Alleghenian orogeny, which uplifted the Appalachians even more. The much loved Pangea formed after Euroamerica collided with Gondwana. As Pangea splinter apart around 200 million years ago, the Atlantic began opening. As it did, Baltica and Siberia moved to form Northern Europe. The eastern part of Avalon was severed from North America and became Ireland, Wales, etc.

Geez, this is starting to feel like a term paper...

Anyway, that's the story, in short. It's actually wildly complicated if you delve into the details of the rock types and structural formations. But to answer your question regarding the majesty of the Whites, yes. They were once very impressively high with great spines of mountain ridges stacking up against one another (imagine pushing a table cloth along the table to form bunched up ridges). I'll show you some geologic maps of New Hampshire and Maine so you can get an idea of how the mountains evolved.

One last thing. Just so you know how clever (or nerdy) geologists can be, in Greek mythology Iapetus was Atlas's father. The Iapetus Ocean was the precursor to the Atlantic Ocean. Neat!

 

[TDawg]

There is also a morraine that builds up under the glaciar. I don't remember the term.

Puck, I think they are termed Ribbed Morraines

 

[dr_wu002]

Well, Dr. Wu, I can tell you a little about the history of the New England and the Whites. It all started with Laurentia, or Proto North America. It was the core from which North America as we know it grew. Around 450 million years ago a chain of island arcs collided with Laurentia in an event known as the Taconic orogeny. Prior to this orogeny, the edge of Laurentia was the Hudson river valley. The Taconic island arcs were accreted onto the Laurentian land mass as part of the continental slap subducted. Next came the collision with the Avalon terrane. Avalonia collided with Baltica (which later became part of northern Europe) and Laurentia about the same time. This event was known at the Acadian orogeny, and involved subduction of dense basalt from Avalonia to subduct under Laurentia. Such subduction was responsible for volcanism on the continent (think of the Cascades on the west coast resulting from the subduction of the Pacific plate under North America). Also, sediments from the Iapetus Ocean were scraped off and accreted onto Laurentia, along with arc volcanics and metamorphics from Avalon. This orogeny started roughly 425 million years ago. The terranes Laurentia, Avalonia, Baltica and later Siberia formed the land mass termed Euroamerica, which collided with Gondwana about 350 million years ago (I'll have to check my dates on this one) in an event called the Alleghenian orogeny, which uplifted the Appalachians even more. The much loved Pangea formed after Euroamerica collided with Gondwana. As Pangea splinter apart around 200 million years ago, the Atlantic began opening. As it did, Baltica and Siberia moved to form Northern Europe. The eastern part of Avalon was severed from North America and became Ireland, Wales, etc.

Geez, this is starting to feel like a term paper...

Anyway, that's the story, in short. It's actually wildly complicated if you delve into the details of the rock types and structural formations. But to answer your question regarding the majesty of the Whites, yes. They were once very impressively high with great spines of mountain ridges stacking up against one another (imagine pushing a table cloth along the table to form bunched up ridges). I'll show you some geologic maps of New Hampshire and Maine so you can get an idea of how the mountains evolved.

One last thing. Just so you know how clever (or nerdy) geologists can be, in Greek mythology Iapetus was Atlas's father. The Iapetus Ocean was the precursor to the Atlantic Ocean. Neat!

Absolutely perfect! You sound like a geologist!

This is exactly what I wanted to hear and it almost sounds like a tale rather than boring geology! There's so much history in all this -- I really enjoy hearing about it and ever since I was a kid I've liked to look at drawings of Pangea and whatnot & wonder what they were like...

Thanks!

-Dr. Wu

 

[Puck]

Anyway, that's the story, in short. It's actually wildly complicated if you delve into the details of the rock types and structural formations. But to answer your question regarding the majesty of the Whites, yes. They were once very impressively high with great spines of mountain ridges stacking up against one another (imagine pushing a table cloth along the table to form bunched up ridges). I'll show you some geologic maps of New Hampshire and Maine so you can get an idea of how the mountains evolved.

One last thing. Just so you know how clever (or nerdy) geologists can be, in Greek mythology Iapetus was Atlas's father. The Iapetus Ocean was the precursor to the Atlantic Ocean. Neat!

Crashing plates, table clothes pushed up into peaks....you must be a real hoot at a dinner party. I would invite you over

 

[Sundog]

Crashing plates, table clothes pushed up into peaks....you must be a real hoot at a dinner party. I would invite you over

Well, I try to behave myself as much as possible...

 

[dr_wu002]

Crashing plates, table clothes pushed up into peaks....you must be a real hoot at a dinner party. I would invite you over

Well, I try to behave myself as much as possible...

Yeah! She's too busy making sure Dr. Wu isn't misbehaving! If anyone is going to be smashing dinner plates and setting tablecloths on fire it's him.

-Dr. Wu

 

[moonrock]

one geologist weighs in

Hi All:

Wow what fun to see so much passionate curiosity (and mercifullly uncharacteristic lack of bad puns!).
Really enjoying reading these posts.

Few points:

ADIRONDACKS (the rocks) are about 3-4 times as old as the Appalachians. They were a previous episode of continental collision and mountain building - possibly with part of what is now South America - but also created some of the rocks found in the oldest APPS.

The original ADKS (Grenville Mtns) were worn flat to a plain, then covered by sandstone, limestone and other sediments, even before the APPS started. Then more dirt washed off the Taconics westward across NY State. Then off the Acadians. Then off the final Appalachian Chain as Africa collided. This, and the later stretching and separation from Africa, created most of the bedrock in New England,more than 100 million years ago. The basalt cliffs and dinosaur tracks in central CT and MA (and NJ) are a gift, from a rift valley similar to that in east Africa today.

Fast Forward: Mostly erosion in the northeast. But then, just a FEW million years ago, things got interesting again: 1) crust under the ADKs started to blister up and form the (new) High Peaks (out of rock that was once 15 MILES underground !), and later 2) climate started to fluctuate, as continents drifted into key positions (Antarctica on south pole, Central America joining NA and SA, Himalayas affecting global winds. Perhaps).

ICE AGES in the NE were a most recent development, starting about 1-2 million years ago (much older periods of glaciation are found, but in different parts of the world (southern Africa) and hundreds of millions of years separate).
Remember: 45 million years ago, long after the dinosaurs, redwood forests still grew north of the Arctic Circle (the stumps are still mummified - and flammible - today)!!!

Based on chemical evidence, continental glaciers (like in Greenland and Antarctica) advanced (and melted back) from Canada/Eurasia a couple of dozen times. Four most recent (or expansive) classic episodes have been characterized from soils in the US and Europe.

Glaciers were the sandpaper, the final sculpting tool. They (or more correctly their base load of rocks and grit - sandpaper requires sand) deepened and rounded the valleys. As a continental ice sheet they covered most - but maybe not all - of the mountains in NY and New England. Imagine standing on top of Marcy or Washington 18,000 years ago and seeing nothing but ice in all directions (except up)! The glacier was perhaps a mile thick in central NY, so ice pressure on the highest mountains may have been secondary to freeze/thaw breaking the rocks. But in the valleys and lowlands the effects were profound. And crustal depression/rebound was about a third of the maximum ice thickness.

During lesser periods, individual or coalescent glaciers occupied the valleys between peaks in the Whites (and the Adirondacks), remnants of which are seen in headwall cirques at Mt Washington (and Gothics and Basin - and also out west in Yosemite).

TILL: was plastered beneath a glacier. Under thick portions of a glacier (or ice sheet), the pressure kept the ground from freezing. This allowed the ice to move relatively unimpeded on a slurry of sand, clay, gravel, and/or boulders. But as you got near the thinner edge (or terminus), the glacier froze to the ground and was overridden from behind by advancing ice. The result was a conveyer belt of dirt and rock, ground up beneath, but then thrust up to the surface, to the ablation zone (where ice melted/evaporated at the surface and left accumulated dirt). This "dirt machine" is what allowed MORAINES to accumulate on Long Island, from material transported south. Interlobate moraines (like large-scale lateral moraines), between medium-scale lobes of ice, occur in eastern Massachusetts and form part of Cape Cod.

DRUMLINS are egg/wedge-shaped landforms, either ground/freeze-thawed from resistant bedrock, or till plastered and sculpted into place. Look at almost any mid-elevation topo map from New England or upstate NY, and you'll see them.

KAMES are stratified sediment that collected on ice along the walls of valleys, then collapsed as the ice melted. ESKERS, collapsed stream deposits mentioned earlier, often are connected to Kames. Look in the 5 ponds area of the upper Oswegatchie, NY

Other obvious features are beaches and clays from early post-glacial lakes like Lake Albany. The clays have a squiggly, gullied topography but the beaches are continuous, smooth slopes above them. Look east of Albany near Route 90.

Would love to expound more, but I'm spent. [It's pouring here too. Finally.]

Moonrock