[HN Gopher] Alpine Crystal Hunters
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Alpine Crystal Hunters
Author : diodorus
Score : 21 points
Date : 2022-09-27 04:38 UTC (2 days ago)
(HTM) web link (www.archaeology.org)
(TXT) w3m dump (www.archaeology.org)
| misja111 wrote:
| I'm surprised that around 5900 B.C. it was apparently more warm
| than now. At least this is what is suggested by the fact that at
| that time the glacier didn't cover that crystal vein.
| Ancapistani wrote:
| The articles says the vein was uncovered recently by a
| _retreating_ glacier, but that it was uncovered previously by
| an _advancing_ glacier.
| misja111 wrote:
| How could it be uncovered by an advancing glacier?
| Ancapistani wrote:
| I read it as the vein having been exposed by the movement
| of the glacier advancing, taking everything that was
| previously above the vein with it and exposing it to the
| surface.
|
| I didn't think the glacier was necessarily present in 5900
| BC.
|
| Now that I've gone back and re-read the article, it looks
| like I was mistaken:
|
| > [H]e came upon a rich vein of rock crystal exposed by a
| retreating glacier.
|
| > The team determined that hunter-gatherers living during
| the Alpine Mesolithic period (ca. 9000-5500 B.C.) visited
| the site as recently as 5900 B.C. and extracted rock
| crystal from the vein, after which it was covered by the
| advancing glacier.
|
| The article seems to be saying that the glacier both
| advanced over the area and retreated from it since 5900 BC.
| That might mean it was warmer then than it is now, but not
| necessarily - the "recent" glaciation could have been
| caused by differences in climate other than temperature,
| like precipitation.
|
| Hypothetically, it could be that it has been warming since
| 5900 BC. Prior to that, the glacier could have existed but
| been relatively static at higher elevation. Warming would
| have caused some to melt, which changed the forces at play
| and caused the glacier to migrate down the slope. That
| would have allowed the vein to be accessible in 5900 BC,
| covered at some point thereafter by the movement of the
| glacier, then be accessible again today due to the glacier
| melting and/or continuing its movement to lower elevations.
|
| There's just not enough information in the article to say
| for sure, and I'm not familiar enough with the state of our
| knowledge of historical climate data to make an educated
| guess.
| misja111 wrote:
| > .. and extracted rock crystal from the vein, after
| which it was covered by the advancing glacier.
|
| I think you read wrong. It says it was covered by the
| advancing glacier, not uncovered. So at 5900 BC the
| glacier had advanced less than now and certainly a lot
| less than say 100 years ago. Doesn't this mean that it
| was warmer at that time, or at the very least, warmer
| some time not too long before 5900 BC?
| bri3d wrote:
| Glaciers slide down hill. As they accumulate mass in the
| accumulation zone, even when it's cold, they are pushed
| down the hill. So a glacier which is growing in size will
| still be moving down hill.
|
| https://asf.alaska.edu/information/glacier-power/glacier-
| pow...
| saiya-jin wrote:
| Its on average around 0.5m/day, but could be up to
| 1m/day. Gravity is too strong force, and they are not
| tightly bonded to bedrock. I would expect that in hard
| winter they move much less but still some.
|
| That's how they keep discovering dead alpinists (more
| like parts of them, ie Reinhold Messner's brother Gunther
| on Nanga Parbat who died there in 1970, I think it was
| piece of femur bone and shoe) in Alps and Himalaya,
| everything that falls down on glacier or into crevasse
| eventually ends up at the snout of glacier (or river
| flowing from it).
|
| Their overall accelerated melting due to climate change
| just accelerates all this since glaciers retreat higher
| and higher.
| misja111 wrote:
| Yes it flows downhill, but as long as ice is accumulated
| in the accumulation zone, which is in the upper region of
| the glacier, the downflowing part is filled up by new ice
| from above.
|
| By the way the article doesn't say that the veins were
| uncovered by the advancing glacier, it says the opposite,
| the advancing glacier covered them.
| [deleted]
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