A comparison of methods used to estimate river rock surface areas

Five methods for estimating the surface areas of river rocks were compared. True surface area was assumed to be estimated most accurately by wrapping the rock in a single layer of aluminum foil. Foil weight and tracing method s provided the closest estimates of true area. A volume displacement method was a poor estimator of area. A caliper method always underestimated true area, although the caliper method was fastest and could be completed in sit u. Predictive relationships were established between true area and caliper method estimates for rocks from two rivers with distinctly different rocky substrates.