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Show The equipment for making a colored thread profile is simple, a snowstake graduated in inches, another stake set up about ten feet away and a supply of colored threads. The procedure is as follows: Stretch a thread between the two stakes and keep it at the level of the old snow. When the thread is well covered by new snowfall, cut it free at both ends so that it becomes part of the snowpack. Record the date when it was buried, the old snow surface, the new snow type, depth and density. Repeat for each principal snowfall throughout the winter. At the close of the winter season, dig a pit alongside the profile to ground level and expose the threads without dislodging them. Recompute the thickness, density and snow type of each layer. Take horizontal and perpendicular resistance profiles. ( Figures Nos. 45 and 46). In this manner each deposit of snow throughout the winter can be positively identified, and the changes which have taken place determined. The data gather so far leads to some expected and some unexpected conclusions: 1. Layer shrinkage does not increase in proportion to age and depth in the snowpack. 2. Dry snow generally shrinks more than damp. 3. Pellet and granular types of snow generally have low rates of shrinkage. 4. Shrinkage is not proportional to the original thickness of the layer. 5. Shrinkage apparently is proportional to density. 6. Layers identified as containing slab type snow originally show a consistently low rate of shrinkage. 7- Apparently eventual resistance to penetration is proportional to shrinkage. 8. There may be a relationship between eventual resistance to penetration and the original snow type. 9. Unless they are very dense, all early and midwinter crusts have a tendency to absorb. Perhaps the most valuable information gained so far from a practical standpoint is the low shrinkage of identified slab layers. See layers E, I and K, Figure 46. This seems to indicate the persistence of slab characteristics throughout a winter. Horizontal resistance was computed by means of the kegelsonde. - Ill - |