Recent comments in /f/askscience

Bob_Skywalker t1_j3zo0tx wrote

Reply to comment by im_dead_sirius in Why are coastlines crinkly near the poles but smooth in the tropics? by emsot

>I think you are remembering that part of geology class somewhat incompletely. That's fine, geology is a huge subject.

I was just making a quick response as noted in my original comment. Hours before you replied I even said it was explained in more depth by comments further down. I was at work, I didn't have time to go into detail.

As far as remembering that part of geology class incompletely, which class are you talking about? Stratification and Sedimentation, Hydrogeology, structural geology, Geophysics, Sedimentology...? Because as I said in my original comment, I have a degree in geology.

Was your entire objective to post your photos, toot your own horn, and act smugly smarter than someone with a degree in the topic at hand? Because it's not a good look.

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Rosevkiet t1_j3zeh3k wrote

Reply to Why are coastlines crinkly near the poles but smooth in the tropics? by emsot

This is a great observation and a good thing to keep in mind for worldle (would have been helpful for the South Atlantic Island the other day).

One of the weirder concepts to wrap your head around in sedimentology is relative sea level. Sea level at any location can change due to local effects, like heavy glaciers loading the crust, actually bowing it down, or for global effects, like changes in global climate or rate of sea floor spreading. It sounds pretty straightforward, but trying to sort out local vs global effects was really hard and took decades.

On a stable coastline, one where relative sea level has been more or less constant for a long time, sediments fill the basin in the water, and the coastline starts to advance out into where the water was before. This is what deltas do. When you look really closely, they are complicated and jagged too, but not on a regional scale.

On a coastline where there is rapidly changing sea level, particularly rapid rises in sea level, all the smoothed coastline will be underwater, and the new coastline will be jagged.

In Earth’s current state, the poles have experienced rapid, recent (50,000 yrs) changes in sea level due to glacial cycles, AND, the erosional pattern of alpine glacier leads to deep, steep valleys (glacier=sediment bulldozer, river = central conveyer belt), so the squiggliness of the coastline will be even more.

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nichogenius t1_j3zee7b wrote

Reply to Why are coastlines crinkly near the poles but smooth in the tropics? by emsot

This might not be the actual cause of what YOU are seeing, but one big difference is caused by many maps using the Mercator projection. The mercator projection (the most common flat map of the world) causes the poles to become very stretched. Smaller features are visible at the poles than at the equator. It's as if you are looking at the poles through a higher magnification than the equator, so your viewpoint is closer to the ground.

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JennaSais t1_j3zcef4 wrote

Reply to comment by Planetary_Epitaph in Why do poultry producers kill their stock when they get bird flu, rather than keeping survivors to reproduce? by poorbill

No, I get that, but I'm saying that unfortunately for this one that horse has already left the barn, so to speak, so if the system changed tomorrow it would be just as bad as far as this virus is concerned. The same mortality rate would apply to those newly-freed chickens. And since it infects other species of fowl (ducks, for example) with less lethality it actually has all the advantages of a lower mortality rate while still being able to infect and be more lethal to chickens, whatever their living situation.

I absolutely believe we need to stop keeping animals of all kinds in conditions like that, to be clear, for this and many other reasons. That's why I got chickens of my own.

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Planetary_Epitaph t1_j3zayuu wrote

Reply to comment by JennaSais in Why do poultry producers kill their stock when they get bird flu, rather than keeping survivors to reproduce? by poorbill

I think you might be half missing the point - the conditions are practically the best case scenario for engendering the creation of extraordinarily virulent diseases, and with such a huge population to infect nearby, high lethality doesn’t have the reproductive evolutionary disadvantages it normally does where the host needs to survive long enough to transmit.

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