I was going for a nice walk today, it was a bit cold, but it didn't bother me too much.

And I didn't too much mind the somewhat cloudy sky, the sprinkled snow on the ground was a nice touch as well.
At one point I came to a spot on the sidewalk where the ground beneath my feet was no longer cement, it was ice.

BUT THIS, this was no fine smooth sheet of ice, this was a cracked earth beneath my feet.

The first crackle that reached me made me believe that I had just found my way onto some broken glass bottle,

but a quick somewhat concerned glance below proved the sound to be otherwise.

The ice, cracked from both myself and no doubt a handful of other average Joes who also daringly walk the streets of Rochester on such a day, got me to think.

After my midday midwinter escapade, and after a few minutes of warming up, I warmed up to the subject of Thermal Shock (this is where the somewhat sciency stuff begins).

This has to do with the cracking of ice, whether from heat or from some guy walking on it.

So, ice breaks, but so does other stuff, ice just might do it a bit more extravagantly, kinda like glass would, because sub atomically it has a crystalline structure to it. 

I'd go more into that, but that's more chemistry.

In physics we like stress (preferably on objects we are testing).

So, the ice is under stress, like when I walked on it, so it cracked; this happened a lot of times and very quickly. 

Of course, stress eventually causes failure, but what about this "Thermal Shock"

Well, your time is precious so I'll do my best to sum it up for you the best I can.

"Thermal shock occurs when a thermal gradient causes different parts of an object to expand by different amounts. This differential expansion can be understood in terms of stress or of strain, equivalently. At some point, this stress can exceed the strength of the material, causing a crack to form. If nothing stops this crack from propagating through the material, it will cause the object's structure to fail."