It doesnt make sense that frost cycles are at work. How many of them are there exactly in a winter? Ten? Plus, below the frostline 50cm below the surface the temp is very stable. Me thinks people detest picking up rocks and do a lousy job.
While erosion can be a factor, rocks rising is quite wide spread and common in areas with very little erosion.
Well, of course it’s done in the Spring!
You have to do it before you start prepping & planting the fields, to protect your equipment.
Here in New England there are actually road signs warning about Frost Heaves. Rocks being brought to the surface by the process of expension of ice due to freezing and re-warming is so common that it’[s a road hazard. Old-time farmers, I’m told, used to talk about New England fields producing crops of stones. It’s not just a matter of soil eroding away – the rocks apoparently are actually brought upwards by the cycle, which can bne a real pain, because it means that a field that has been cleared of stones won’t stay that way, and must periodically be reswept. It gives credence to the claim that a lot of those picturesque stone walls New England is known for aren’t so much boundarires as threy are “stone dumps”, places to get rid of the big rocks that are clogging up the fields.
Ayuh, I’m well aware of that. Comment was for the general enlightenment and edification of those Dopers who’ve never worked the boat and whose only contact with foodstuffs occurs in the grocery store.
I agree, I was just disagreeing (or possibly misreading) a statement that I believed read as ruling out erosion.
In truth, I must admit an answer that suggested erosion wasn’t a factor at all. Anybody that has driven by a plowed field after a rain has to admit it is part of it.
I would like to see more discussion on whether they rise below the frost line.
microtremors happen and can move soil particles down below larger rocks.
also rain/flood/snow-melt may move loose soil particles. as water moves through the soil it might give a push to soil particles and they might move into any void on the downward side. water might hit a rock and flow around it, the bottom side may provide a lower resistance channel for it to flow; that channel constantly gets refilled with soil and a new channel made causing the rock to be lifted one soil grain dimension at a time. given long enough there would be movement.
I would too, with or without frost being a part of it. I live in western Washington where we have surface frost and very mild snow, but the ground never freezes. However, I have seen all kinds of things migrating upward - rocks, chunks of cement, buried tend poles, buried pots, etc. If it’s erosion, then the trees and my landscaping are all sinking to keep pace with the erosion.
My WAG is that it has to do with changing moisture levels causing the soil at different levels to expand at different rates, which permits small particles to settle down and large ones to shift up. But I’ve never been able to find any research to confirm or deny this.
Anyone who has lived near a fault line and kept up on geological explanations would say that plate tectonics has some influence on the rock migration.
Granted, the forces of plate techtonics are minute to the human lifespan, but that’s the big stuff. The earth underneath your feet is NOT static.
~VOW
Personally I hate rocks migrating through the soil.
Look !We’ve got enough of our own rocks here OK ?
You Quartzs, you Granites, just fuck off back to your own sub stratum,
You’re not wanted here alright !
This is a Sedimentary area, and we also don’t like volcanic magmas moving into our neighborhoods .
Don’t say you weren’t warned !
throw some rocks at them, that will scare them away.