About 45 centimetres of dry, yellowish grey diatomite occurs under 60 to 90 centimetres of soil in the meadows where Woods Creek joins Pukaist Creek. Immediately under the diatomite is a thin bed of chocolate-coloured clay which is underlain by slate-grey clay. It should be noted that this area is now under tailings waste from the Highland Valley operations.

The valley and meadows at the junction of Woods and Pukaist creeks extend northeast for at least 9 kilometres and in many places over this area test holes showed thin beds of diatomite under 60 to 90 centimetres of soil (CANMET Report 691).