Tuesday, 22 May 2007

brazil nuts, garden stones and avalanches

Isn't it annoying that garden/fields seem to grow stones.
I wonder is it maybe http://en.wikipedia.org/wiki/Brazil_nut_effect

Cool. I want a jar of beetles, sand and pebbles on my desk too!


"Avalanches are gravitational granular flows,"

"When the avalanche flows over a terrain feature (steeper slope or surface irregularities), the flow can become turbulent (mixing) causing the victim to be pushed down. As the flow smoothes out, it is the particles segregating (de-mixing) that force the person back to surface."

"When an avalanche slows (but before it stops), the snow fragments interlock, resulting in a
change in state from a fluid-like flow to that of a sliding block (everything moves as a single unit or block)."

So. Esentially. Keep arms near face somehow.


mopti said...

The brazil nut effect is at work in my back garden.

I also have two larger rocks that need more serious attention: the upper surface one the higher one is (well, "was" until I excavated a few weeks ago while trying to plant potatoes) just 10 cm below the surface of the "lawn". Digging to see how big it is (0.5m^2 on the top surface, depth unknown), I discovered a second one a little bit deeper and just as big.

My Dad (who grew up on a farm a mile away) says the area is stoney. He suggested I dig a hole beside the large rocks and topple them into it.

I have named the first rock I found "Gibraltar", and when I discovered the second one, I named it "Caesar" (I come to bury it, not to raise it).

gaoithe said...

lol! :-D

We have remains of our eucalyptus tree trunk now in prime position at front of house (upended).
Looks like a mushroom - maybe morel eucalypta really giganticus.

I had an epic dig last year as well as the exciting time chopping down (and up) the eucalyptus.
Our grassy bits were always hard and not so nice.
Back and front of house had been used as road when houses were built about 16 years ago. Rotivator could do top few inches but dug whole garden with fork so could rotivate deeper. Rotivator was like holding on to a few angry boars.

Eucalyptus was good for climbing and holding hammock and bird boxes.
That's Daire & John my brother & the tree.
Quite liked it but knew they grow fast & big.
Every year chopped sizable limbs off of it. Was amazed how much timber it generated!
Now the grass has very root-like healthy lines radiating from where tree was.