> distinct entity within the mantle for an extremely long time.

Why don't they just melt?

Are there fossils burried in the mantle?

They sort of obliquely refer to it, but omitted the attraction of clay to the surface of the grog/sand particles- the clay would rather stick to each particle than allow gravity or other force to separate them. this bond is “fluxed” by moisture while workable (a pug or other milling process acting just like a mason back-buttering stone/brick/tile) but once smeared all over each particle, the drying phase doesn’t weaken the bond and the particles of sand are each captured by clay, the clay wants to stick to itself and the sand so it cannot shrink- the loss of moisture instead creating tiny pores and a lattice of strong bonds like a huge brick cube. During firing, the clay is welded/“brazed” to each particle so you get enormous compressive strength.

This is a good visual representation of climate throughout earth’s geological history. Notice how slow most of these changes are, a matter of a couple of Celsius change over millions of years. Then look at the change over the last 200 years.

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No, that has nothing to do with that. We're talking WAY different scales here.

For life to develop you do need some stability of course, I mean, a supernova going off next door won't be helpful. :-) But for life we're talking about the local environment. Things like: how far is the nearest star? What is the chance of trouble nearby?

As for a crowded set of Galaxies, the chance of galaxy collisions is indeed higher, but when galaxies collide, in general, stars do not collide. You do get a BUNCH of new star formation, but locally things can still be stable. Looking at individual galaxies within the Virgo cluster we're not seeing much different structures like what we see in our own Milky Way...

Moreover, price. If you want a new target you dont have to make a whole batch of new signalling AB just the primary AB of the same origin as before so they too can be targeted by the secondary AB.

I'm going to take a stab at this. Hope I don't get too complex even though the question is really several questions.

Glacial ice is mostly the result of past snowfall. Ice is what you get when you compact the snow and get rid of all the open space. It is pretty much the same idea as the conversion of mud into rock. The snow undergoes metamorphism in a away, it recrystallizes from pressure (weight) perhaps with some melting, flow of water down into open space, refreezing, as well.

As you know, we live on a seasonal planet. The result is that there is seasonality in precipitation and temperature. These variations cause ice to form distinct layers for each year, very much like how tree rings form and the thickness of the rings reflects what went on with the weather during that year. Some rings (some layers) can be fairly thick, and some are almost non-existent depending on what happened over the course of the year. Dry year, not much snow=thin layer.

Loose snow can be 80-90 percent air, or to put it another way, you get about 10 inches of snow for 1 inch of rain. The conversion is ballpark, not precise. I am sure you have heard something along those lines, and the point being made is that water, liquid water, has a density of about 1 (g per cubic centimeter) but snow has a density of about 0.1. Only 10 percent. When converted to ice, the ice will have a density slightly less than water (why ice floats in water).

So, you lose about 90 percent of the volume even if no melting or sublimation (evaporation but without passing through a liquid state, from solid to vapor directly). Apparently about half that density change from snow to ice happens in the first year. (makes stuff called firn, snow from previous winters that has not converted into solid ice) and the rest happens over several years or more.

That is how we go from snow to glacier. How much snow? Well, that really varies a lot. Some places will only see maybe a meter of snow per year, and other places maybe 10 meters or more, with most places having permanently winter conditions getting something in between.

Lots of places still see some above-freezing or near freezing temperatures so sunlight heats the snow to melting, during part of the year (like say on high mountains) so part of the snowpack gets lost by melting and evaporation/sublimation. So in many regions, the amount of original snowfall that makes it down into ice might only be a small percent of the original, perhaps 10-20 percent. So, if we started with a meter of snow per year, we might only get about 5 cm of ice. Still, even at that slow rate, you could get 5 meters in a century and 500 meters in 10,000 years.

So, how fast does it accumulate? You can get some pretty important changes to ice extent and thickness over the period of a millennium (1,000 years), even when there is not a lot of snowfall, but generally it will be slower even if there is a lot of snow (because of loss through evaporation/sublimation and melt runoff).

Many thousands of years is generally needed to make a good glacier and tens of thousands of years to make an ice sheet (massive glacier). Some ice sheets, like in Greenland, have been drilled and cores removed, going back 100,000 years, and even further back, several hundred thousand years, in the Antarctica ice sheet.

Africa has largely missed on continental glaciation because it is too close to the equator, or too far from the poles. Mountain glaciers and flow onto nearby lowlands is indicated, but no massive ice sheets. Same idea with Australia. South America had a pretty well-glaciated spine almost up to the equator (the Andes mountains are so high that glaciers could be formed even near the equator), but much of the continent did not get glacial cover.

Two reasons why the northern hemisphere got a lot more glacial cover than the southern hemisphere: 1) the Arctic is an ocean so lots of moisture can be transferred to nearby land, and 2) a lot more land in the northern hemisphere is near and in the polar regions than in the southern hemisphere.

The ice sheets in the northern hemisphere mostly never got further south than about 45 degrees N. Most of Australia, Africa, and SOuth America, is further north than 45 degrees south. Basically southern lands a lot further from the south pole than northern lands from the north pole. Apart from Antarctica, of course. Frozen pretty solid down there.

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That's not really a guarantee, it's entirely possible to push a planet into runaway greenhouse mode and it never recover to where carbon/DNA based life is possible again.

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That’s fair. I mean we definitely can be helping things by speeding up, or even completely changing the natural process.

The natural balance will eventually be restored. Just a question if we’re still around to witness it

Are you under the impression that heritability of height is defined as the correlation between children's heights and the average of their parents' heights? Obviously you can determine that by calculating said correlation, but that's not what heritability means.

Heritability refers specifically to share of variation in a trait attributable to genetic variation. I suppose it's possible that there's some field other than genetics in which the term is used to refer to the degree to which children are similar to their parents, but the original question specifically referred to the definition used in genetics, and you definitely can't calculate that by comparing children to their parents. If you could, twin studies would never have been invented. That's the exact problem they were invented to solve.

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Is it a coincidence that ice has been close to the magnetic north and south poles? I searched for information, but only found that the ice caps are made up of fresh water, which has a lower electrical conductivity than salt water or rock, and act as a barrier to the flow of electrical currents in the Earth's crust, and this can affect the magnetic field in their vicinity.

This video lecture from Nick Zentner featuring Karin Sigloch has some great tomographic imagery of subducted plates in the mantle!

Skip to around 56 min in if you just want the imagery: https://www.youtube.com/live/l0z3p8ypZKY?feature=share

This paper from Sigloch & Mihalynuk has some great imagery/models of subducted slabs, including some of the ones used in Karin Sigloch's presentation above.

Edit: Attached this to the correct comment this time!

Okay yeah that makes sense thank you!

Yeah, well, there is the nub of the argument, and a good part of the reason why most scientists accept that humans are affecting climate but many disagree about the importance of the human role. It is also where a lot of uncertainty appears in predicting into the future.

The problem is that there is no "signature" we can measure directly and say "this 23 % is from humans (pick any number), and the other 77% is what nature does".

What we have are climate models. The climate models are an attempt to imitate the natural system behavior, and seeing how different changes to input conditions cause changes to output. The system is complicated, and so are the models.

There has been a lot of work on trying to figure out how much change has been "forced" by human activities versus how much can be explained by natural changes. They can compare models with, or without, changes to various important parameters over time as an input, and see how the results differ, and then interpret what is really important and what is not so important for what is actually happening. Fairly complicated work in actual practice.

It is from playing around with the various parameters that can affect climate, and finding mismatch between observation and the changes that ought to have happened if nature alone is the cause, that a lot of climate scientists have concluded that CO2 is the main problem.

Are they right? We are finding out. Not sure it is wise to perform this experiment in real time, but we are, even if not purposefully.

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Signal amplification. The primary antibody is relatively unencumbered of detection tags, so can maximally bind it's target unimpeded. The secondary, often polyclonal, can bind multiple sites on the primary Ig antibody that's already attached to the target molecule. So multiple molecules of secondary (labeled) can attach to each primary antibody, thereby increasing signal strength, whether fluorescence, chemiluminiscence or colorimetric, versus using a labeled primary antibody alone.

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