NATIONAL PARK SERVICE Wolf Ecology and Prey Relationships on Isle Royale

Notes on snow-analysis equipment and procedure.

1. In 1972 and 1973 a compaction gauge similar to that described by Verme (1968) was used. The compaction gauge (cross-sectional area: 1.98 cm²) could be loaded with lead weights to simulate any load up to 65.0 g/cm². The general procedure was to begin at 100 g/cm², and increase the weight load until the instrument reached the ground when dropped from the snow surface. Because of the great variability in snow cover, 10 or more readings were taken for each weight load, at increments of 50 g/cm².

2. In 1974 a Rammsonde (Ram) penetrometer replaced the compaction gauge as the preferred instrument with which to measure the support quality of the snow. This consists of a stainless steel rod tipped with a 120° cone, 10cm in diameter. A 1-kg drop hammer was dropped from a given height (30cm was used) along a guide rod, forcing the Ram into the snowpack. The depth after each blow was recorded, until the tip penetrated to within 3cm of the ground surface. The Ram hardness number was computed from the following expression (Testlab 1970; Coady 1974a):

10R=	Whn	+ W + Q, where
	x

R = Ram hardness drop
W = weight of drop hammer (kg)
h = height of drop (cm)
n = number of hammer blows
x = penetration after n blows (cm)
Q = weight of penetrometer (kg)

3. Density of snow was determined by weighing 500 ml of snow extracted from the snow profile with a Testlab snow cutter. Show hardness was measured with a Chatillon "Push-Putt" gauge fitted with circular plates measuring 1, 10, or 100cm in area. The gauge measured up to 1000 g of force, and a sliding disc measured the greatest force obtained on a single trial. The plates were placed flat against the snow surface to be tested and a force applied until the snow structure collapsed, as described by Klein et al. (1950).