OCR Text |
Show Accelerated Metamorphism Percolation of free water Air pockets Depth hoar The, last two might bear explanation. Regarding the air pockets, their location will vary according to factors involved. If ground temperature is warm, particularly if new snow is deposited on bare ground, air pockets tend to form at the ground- snow interface. If a crust or ice layer is present in the snow pack, and if this layer is strong enough to support subsequent layers, the layers immediately below this crust will have a tendency to settle away from the crust. This has been found to be common, particularly if the snow type under the crust is recently deposited large crystals and had not had time to undergo metamorphic change prior to the crust formation on top of it. For example: A rain crust formation at the end of one storm cycle, immediately followed by another with additional new snow. The air pocfkets themselves will vary greatly in size; from very small to 2" high by 12 to 16" in diameter under crust layers, and up to k" high at ground surface. At times these pockets have been numerous enough to leave less than 50% of the layer surfaces bonding. The inner surfaces, or walls, of these pockets are mostly very uneven. Within the snow pack they are composed primarily of chunks of semi- frozen crust, easily crumbled by hand, at the ground surface the appearance is the same, but samples of the cavity walls crumble into slush when touched. |