Question

what composition of transformations describe footprints left in snow

Answer 1

Reflection is out, because the foot print is always the exact form of the shoe, and the snow doesn't somehow flip into itself.
Rotation is out as well since the snow doesn't turn to the side when stepped on, nor does the footprint show the signs of your boot from an angle

The only change is that the snow has been shifted downwards

Answer 2

Compressed a little even