how thick does i ce need to be before it becomes a moving glacier?

Answer 1

There's no hard and fast rule here because there are other factors involved:-

The ice has to reach a certain thickness to have sufficient weight to overcome the friction of the ground it rests on but that in turn depends on such factors as:-
+ the steepness of the slope
+ the type of material the slope is made of (some generate more friction than others)
+ ice itself isn't all the same - often it consists of layers of different densities and one layer may slide over another
+ the weight of snow pushing the top of the glacier down
+ the resistance of the material at the end of the glacier
+ the temperature - in slightly warmer conditions more water may get under the glacier and reduce the friction

Answer 2

From Wikipedia:
"Ice behaves like an easily breaking solid until its thickness exceeds about 50 meters (160 ft)."

Slope of the underlying terrain and surface slope both affect this thickness. Composition of the underlying terrain has a great effect on the coefficient of friction. Altitude and latitude of the glacier also have an effect.

Answer 3

I think this is kind of like asking when a piece of land is big enough to turn from a "cape" to a "peninsula". If the ice is heavy enough to "flow" then I guess it's technically a glacier.

Answer 4

the largest glaciers in antarctica are about a kilometer thick - the smallest ones in the himalayas are about 12m.
go figure it out.