For classifying sand from coarse to silt. Flexible,
water-resistant plastic card helps determine size
classification, bed thickness and roundness of sand granules.
It includes a field checklist to organize field notes,
geological time scale, and two carbonate classification
charts. Actual sand grains are fused to the plastic 2 1/2" x 3
1/2" with lanyard.
Gage 0.3 lb.