A line drawn N. W. and S. E. about half a mile north of the church
town, will divide this parish so into two unequal parts, that the
northern, by far the most extensive, will be found to rest on granite,
forming a barren waste for several miles in extent; its valleys,
however, have afforded stream tin in considerable quantities, and of
the very best quality, rendering it therefore probable that this
valuable and rare metal may exist in the granite more than has
generally been supposed. The other portion of the parish is situated
on slate, resembling that of the parishes of Cardinham and St. Clear,
immediately in the vicinity.