jonwvara 

I'm sure that many longtime members of this forum were disturbed to learn of a possible misinterpretation of the serial numbering of Centurion brand bicycles. This in itself is bad enough, but it gets worse. Please bear with me, because this will take a moment to explain.

I am not a devout Christian, but have been a lifelong celebrant of a religious holiday known as "Christmas." One aspect of this holiday involves the exchange of gifts among friends and family members. In one such exchange, I recently acquired a well-regarded nonfiction book from a major publisher, titled Mill Town. Written by a former resident of Mexico, Maine, it examines the long-term health and environmental effects of paper manufacturing in the town of Rumford, Maine.

On page two of the book, the following sentence appears:

"In the deep grottoes of the past, the great polar ice cap melted into glaciers, and its calving mass crawled north, carving long, deep ruts that became the lakes and rivers of Maine." [italics mine]

Reading the above filled me with surprise. I had always believed that the continental ice sheets of North America's last glaciation had moved from north to south, not south to north. And indeed, subsequent research seems to confirm that my original concept was correct. As unlikely as it seems, it appears that the quoted sentence is--and it gives me no pleasure to write these words, not wanting to cause unhappiness to the author or editors associated with the book's production--flatly incorrect.

This is knowledge that we will all have to live with from now on. I hope and pray that there are no other books out there that contain factual errors. But sadly, that possibility cannot be ruled out.

Be safe, everyone.

iab

I also object to the word "melt" as it indicates phase change whereas compressed, squeezed, extrude, etc would be accurate.

What this has to do with bikes, I haven't a ******g clue.

iab

Unless of course the author is claiming the melting of the glaciers, from south to north, did the carving. And the water runoff did do its fair share of carving. Either way, poor writing.

What this has to do with bikes, I haven't a ******g clue.

nlerner

But it's in a book! It must be true!

I understand that the Centurion serial # hoax is associated with an obscure millennial sect known as the Takarians, who purport to advocate for feeding babies tubular tires.

Swampthing 

Yea. Scary
Someone told me about that.
someone should start a petition.

Reynolds 

I've heard all that glacier melting, climate change stuff is a big hoax.

jonwvara 

1. Ice sheet carves river valleys.
2. Road system is later superimposed on existing river valleys.
3. Bicycles and other wheeled vehicles use roads superimposed on etc., etc.

iab

Yet your more interesting places to ride had an absence of glaciers. Just sayin.

jonwvara 

Yeah, no denying that. Plus the glaciers filled my fields all full of rocks. The bastids!

TimmyT 

Glaciologist checking in here.

Retreat is south to north. The advance maxes out 22-18 thousand years ago. While I don't recall the exact history for Maine, it's probably fully deglaciated by 12-14 thousand years ago.

The general cycle is that snow falls on the ice sheet. The weight of the snow compresses it to ice. The ice flows under its own weight (similar to watching honey level itself off on a spoon). The ice flows from the accumulation area (where snow falls) to the ablation area (where it melts and sublimates). The melting happens almost exclusively in the summertime.

As climate warms, the summers get warmer. Warmer summers mean longer summers for the ice sheet -- the time of melting is lnoger. The amount of melt exceeds the amount of snowfall causing the ice sheet to retreat.

This is where it might get confusing: the ice is flowing south, but the ultimate extent (what we refer to as the margin) is moving north.

Because the summertime melt is high during retreat, there is a lot of "excess" water that carves the landscape. We almost never see the growth phase of the ice sheet on the land surface because the retreat phase is so strong and it's the last thing to happen.

I hope this helps.

nlerner

Yeah, back in the day we'd pack up some snacks, hike up to the ridge, and watch the ice flow retreat.

TimmyT 

Did you ride your highwheeler to the trail head?

nlerner

Mostly but no trail heads back then. We had to bushwhack.

machinist42

I attribute any and all anomalous local glacier events to the "Glacier Mice."
(They field the blame for much here.)

Germany_chris

I agree Ergos are better than STI

majmt

Deep Frozen Arctic Microbes Are Waking Up

https://www.scientificamerican.com/article/deep-frozen-arctic-microbes-are-waking-up/

Markeologist

Clearly the sentence is referencing the period when the glaciers are receding (it states "melting") as the planet warmed and thus the southern edge of the ice sheet was moving northwards (i.e., receding as opposed to advancing)....kind of basic earth science to all but the troll who denies glaciation occurred.

iab

Clearly, it also states "calving", which is quite the opposite of melting. All in all, it is a ****ed-up sentence.

Markeologist

True, sentence is poorly worded but calving is absolutely not the opposite of melting. Calving occurs at the edge/margins of the glacier, large masses of ice breaking free of the ice sheet, a process that can be exasperated by melting of the ice sheet. "Can" being the operative word here but don't get hung up on that. The original question focused on the movement of the glaciers (northward vs southward). As I and others have posted, it depends on at what period/point in time is being discussed. Since the sentence stated that the glaciers were melting that indicated during a warming period when the ice sheets were receding (i.e., shrinking towards north). Even in periods of recession, the glaciers still affected the underlying topography.

conspiratemus1

Very much, thanks. One of the hallmarks of glaciation near my neck of the woods is the U-shaped valley with hanging waterfalls. The Finger Lakes region has some excellent examples, but there are less striking ones along the Niagara Escarpment. In more mountainous regions like the "Canadian" Rockies (defined as extending south to Marias Pass, Montana, so including Glacier Park) and the western shore of Newfoundland they make spectacular landforms. These started out as V-shaped valleys but we see them today as U-shaped. I wasn't around to eye-witness any of that. So were the valleys scoured out by the weight of the advancing ice pushing the rocks ahead of it? ... or flooded out by the torrential meltwater during retreat? Until the ice retreated enough to open the St. Lawrence valley, "Lake Iroquois" (now Lakes Ontario, Erie, and part of Huron) drained out through the Finger Lakes to the Atlantic via the Susquehanna River. That's a heck of a lot of water. I understand there is some controversy around the shaping of these valleys and I'd value your thoughts.

stevel610 

We need to bring back leather hairnet helmets.

I am also quite pleased that glaciers have melted, whether North to South or vice versa, as riding on roads is much easier than glaciers.

WGB

There are books with confirmed errors or even possible errors, about glaciers? I guess there are. I expect very very few books could ever be perfect. I have no clue about glaciers. It appears some members do. My question repeats the one above from iab What this has to do with bikes, I haven't a ******g clue.

Wouldn't this fit better on FOO??

gugie 

What I got out of this is we should ditch our gravel bikes, and find vintage glacier bikes, stat.

ascherer 

Corresponding rush on studded tires...

seypat

The only thing I got out of the thread is that Canteen Dave must have died in a glacier drinking his Deer Park water on the Appalachian Trail in Maine. I haven't heard him hawking Deer Park water in a long time.