Two years ago, over at WattsUpWithThat.com, my friend Canadian climatologist Rodney Chilton posted an article on the Younger Dryas and the Thermohaline Conveyor shutdown that is supposed to have happened. I was one of the people who vetted and edited Rodney’s paper, so it is something I had a little hand in. Rodney duly gave me credit in the Acknowledgements, even. I was quite pleased to see how many commenters at WUWT had positive comments.
I am not going to comment directly on either of the topics, but will instead disuss a comment by a guy named commieBob, which was replied to by a handful of people, with a couple of them actually not having any idea what they were talking about or what science’s take was on the point of commieBob’s comment.
I did myself read the linked article, which had some valid points and some mish-mash in it. I will pass on the mish-mash and address what I think are valid points.
To this, one comment was the following. I will comment here on the bolded parts of davidmhoffer’s comment:
So what am I going to write about this?….
Hoffer cheated a bit on his quote of the article, by leaving out the middle paragraph of what he pasted in. Here it is:
“If a solid be so heavy and so big that it requires more than a certain force to move it, it will crush rather than move, that is to say, the whole thrust will be dissipated by the object being reduced to pulp, or even liquid, which will flow away rather than move en masse.” [ Howorth, H.H. 1905 Ice or Water? vol 1, p383]
Now, Howorth had his physics and materials science right. He evidently was one of the last battlers against the ice age theory, a bit over 100 years ago. A very young Louis Agassiz started it in 1840, as the article correctly states. He sold Charles Lyell on it, and Lyell, THE big name in geology at the time, needed it as the last piece of his Uniformitarian puzzle. Agassiz, happy to have the great Lyell on his side, let Lyell even talk him out of multiple ice ages, which is what Agassiz saw. Lyell insisted on only one, proving that he wasn’t interested in facts that confused the issue. Of course, later evidence showed that there was more than one “advance” of the ice – according to Agassiz’ interpretation and later ones who pick up on his work. Darwin’s/Wallace’s natural selection/evolution came along a few decades and added to the Uniformitarian-Gradualist theme.
Now, let’s go back to the bold portions…
It is interesting that Hoffer starts with “I’m darn sure…” because that phrase means that he is NOT sure at all.
“An “ice age” happens when the total amount of snow that falls in winter exceeds the amount that melts in summer.” With this Hoffer shows that he does not know that the start of ice ages has actually been discussed on WUWT several times. The main misunderstanding that most people have about ice ages is that they think ice ages start and build up via cold weather and that the cold weather brings more snow. As Rodney points out in his article, this is not true. Extended cold weather actually brings a drought situation, because in order for it to snow, WARMER weather is needed in the high latitudes. Water does not evaporate at cold temps, and colder air holds sufficient humidity to create large snowfalls. Antarctica, for example, is a desert. Look it up!
If that happens over a large area, you get a large ice sheet, it doesn’t have to “travel” to get anywhere. With this, Hoffer shows that he is not conversant with the prevailing academic mentality about the N American ice sheets. Nearly ever paper discusses the “advance” of the ice – especially in the Great Lakes region. It is talked about as moving down about 22,000 years ago to what is called the last Glacial Maximum. Hoffer also seems to not understand a thing about the thinking on moraines. Let’s see how Wikipedia summarizes moraines and how they form:
A moraine is any glacially formed accumulation of unconsolidated glacial debris (soil and rock) that occurs in currently glaciated and formerly glaciated regions, such as those areas acted upon by a past glacial maximum. This debris may have been plucked off a valley floor as a glacier advanced or may have fallen off the valley walls as a result of frost wedging or landslide. Moraines may be composed of debris ranging in size from silt-sized glacial flour to large boulders. The debris is typically sub-angular to rounded in shape.
The very existence of lateral and end moraines tells us that rocks were moved and piled up at the end of the movement.
Now let’s look at Howorth’s statement (see above). A basic mechanical principle is that every object that has any force applied to it depends on its internal strength to RESIST the applied force, which is called the Reaction Force. It is basic physics and not subject to interpretation. It is the way things are in the physical word/reality. There are two forces involved – the APPLIED force and the REACTION force.
An example is a building’s steel structure. The building weighs a certain amount, and that weight is composed of a DEAD LOAD – the supporting steel itself – and the LIVE LOAD – the things IN the building that are not part of supporting it (desks, wallboard, toilets, ceiling materials, doors, humans, etc.). Obviously, near the top of the building the dead+live loads on the structure up there is smaller than down below. And each level down needs a little more strength. Steel DOES fail, if over loaded.
More applicable to Howorth’s point – and that Hoffer misses – is the strength of the soil beneath the foundation. Many of us are familiar with houses “settling”. What – in the engineering sense – is actually going on with settling? Settling comes from an inadequate UNIT STRENGTH (pounds per square foot) in the soil. That is why for big buildings and even some homes soil tests are required. Why? To find out how string the soil is. If it is not strong enough, the weight of the building will slowly CRUSH the soil. The house compresses it more than the soil is capable of RESISTING, so the soil gets compacted – pushed downward and squeezed downward. All soils are not equally strong – and NONE are infinitely strong. So tests tell what ability the soil has to resist the weight it will be asked to support. If it is inadequate, measures need to be taken to ensure that the soil strength is bolstered or NOT EXCEEDED. That is the engineering that goes into foundation design. This is all REAL, not imaginary. Materials have limits, and those limits need to be known and accounted for.
Essentially, this same principle is what Howarth wrote about in 1905. As soils are not infinitely strong, neither is ice in ice sheets or glaciers. Howarth saying that the lateral forces necessary to overcome flat ground or bumpy ground friction is not a joke. Howarth saying that the ice internal strength is limited is not a joke. Howarth saying that the lateral forces needed to move ice may be so high that the internal strength of the ice – like soil under a building – may be too weak. Howarth says that the forces needed ARE too high – that the ice is too weak.
This may, indeed, be true. The lateral forces needed to push ice laterally over rough ground may truly be more than ice can resist. And what would happen in that case? Howarth says the ice would crush. ANY material – steel, aluminum, wood, ice, plastic, ceramics – has a known strength. Different alloys of metals have different strengths. Different ice conditions will make ice stronger or weaker. Increasing cold makes ice stronger. Increasing warmth makes ice weaker. Other conditions that exist – some during the freezing cycle and some later (pressure, for one) – can make ice stronger or weaker. At no time does ice have infinite strength internally with which to resist an applied force. (Neither do steels of other materials.)
So, at SOME point – SOME applied force – ice will fail. Howarth calls it “crushing,” and that is as good a word as any. What happens is that the ice crystals have weak planes between crystals, and these will fail first. In mechanical engineering – which is applied physics – this failure is called “shearing.” The crystals shear along the weak planes between crystals. NONE OF THIS IS MADE UP; IT IS REAL WORLD SCIENCE. If a material is too weak, it fails. Collectively, when ice shears it is seen as cracks. When a load is applied over a large face and the face fails, the ice crumbles – it is crushed. Howarth is not wrong on that principle. Are his numbers right? They may well be. What does that mean?
It DOES take a minimum total force to move ice horizontally over flat or rough flat ground. The more ice that needs to be moved, both thickness-wise and length-wise, obviously the more force has to be applied to the back end of the ice.
Now it is necessary to discuss the differences between glaciers and ice sheets. Glaciers exist in mountain valleys. Glaciers are rivers of ice. Like rivers, glaciers can only exist at the bottom of valleys. Like a river, a glacier fills up its valley to a certain extent. Like a river, gravity makes a glacier flow. The slope/angle of the valley floor (top to bottom) determines how much lateral force pushes the glacier down along the valley floor. Gravity, as we all know, is vertical. So the lower the slope/angle, the less of the force of gravity is available to push down the slope. At a high slope, the push down the slope is higher. At a lower slope the push down the slope is less. What happens when the slope is flat? There will be no gravity force to push the ice sideways. What happens with a very low slope? Very little gravity slope is available to push the ice down the slope. There is nothing rocket science about this – it is simple trigonometry. Ice sheets as depicted in North America – in Canada and the northern tier of states in the USA – are essentially on flat ground.
So, what does all that mean? Let’s see how much slope there is in a typical Alpine glacier and compare it to eastern Canada and Michigan, where the LGM – last glacial maximum – existed, according to current thinking. Let’s select the Mer de Glace in Switzerland, and then Eastern Canada down to Michigan. The Mer de Glace is about 1045 km long from the rock just above the top of the glacier, down to the moraine at the bottom. In that length the glacier drops from 3255 meters to 1490 meters – a drop of 1755 meters. The slope comes out to be 16.89%.
I can tell you that THAT is STEEP. I live in a town with steep streets. My own is 21%. Another steep one here is about 16%. You should see the river torrents when it rains, coming down these slopes. Gravity at work!
Now, how about Eastern Canada down to Michigan. The centroid of the last glacial maximum was east of Hudson Bay, with a thickness there of about 2 km, which was THE thickest point in the ice sheet. The elevation varies, but is about 170 meters to about 400 meters, for an average of about 300 meters. Michigan has an elevation of about – guess what? Right about 250 to 400 meters – almost the same as that area east of Hudson Bay. What does that mean? It means that the land is flat for about the entire 1700 km – with some ups and some downs. And Lake Huron and Lake Superior are in between, too. Ouch! So, with a basically dead flat terrain for those 1700 km, what is the trig value for the lateral forces? Would you guess ZERO? If you did, you guessed right. The weight of the ice east of Hudson Bay basically does nothing but push the ice sheet straight down onto the ground. And SITS.
Now, does that even SOUND right? You should actually be asking that.
An Experiment to Try
As a small experiment, in the winter and it is below freezing, go out on a flat asphalt pavement, which is relatively smooth. Find a place where water will not run off – but find a place where it is NOT going to puddle before freezing. Then pour water SLOWLY on that spot and let it freeze. Pour more water SLOWLY, and let THAT freeze, too, and keep doing it SLOWLY until the ice is THICK. If you pour it fast, it will not simulate the slow build-up of ice sheet in Canada.
I am predicting that the water will run over the top of the ice and some will run off, adding to its area. It will spread out, – more or less what Hoffer argued. But remember that Hoffer talked about SNOW, not water. A few inches per minute of water flow over that ice puddle would represent ice flowing at many miles per hour from Hudson Bay. That is why you want to pour very slowly. No ice sheet moves at many miles per hour. Even glaciers don’t when they are flowing down Alpine valleys.
An even simpler experiment is to just put ice cubes on the flat ground and watch them. Watch them not move. Then put them on different slopes and watch them. With enough tilt, they will move. Without enough, they won’t. It is REALLY complicated. NOT.
So, one of the things we are finding out is that the ice did NOT have any lateral vectors deriving from the gravity. Not to speak of, anyway. Zero elevation difference in 1700 km does NOT equate to a lateral force. EVEN IF we take the drop in elevation as the full 2 km height of the ice sheet, what do we get for a slope? We should do that, right? What do we get? A slope of 0.117%. For every kilogram pushing downward, the lateral force would be only 0.0014 kg. Is that sufficient? No. That won’t overcome the friction of the ground, much less push the ice.
Glaciers Are Not Ice Sheets – and Vice Versa
We are finding that Alpine glaciers have a VERY steep slope to them, which means what? HIGH lateral vectors deriving from gravity. Vectors equal force. SO when someone talks about glaciers and ice sheets (at least in N America), be fully aware that the two are completely different animals. One is flowing down steep valleys, and the other is SITTING on flat ground. One moves easily enough by gravity (though it still has to overcome a great deal of friction). The other cannot move. Ergo, no “advancing ice sheet” no matter how many times it is asserted. Physics is physics.
So, where does that leave the ice age theory? What DID happen if ice sheets didn’t advance? How did the ice get so far south? That is for another time, another post…