(c) Dikes.

Dike rocks, both acid and basic, are commonly in the basement complex. Age relationships were established in most cases between various types. Acid types are leucocratic and consist mainly of quartz and feldspar, and range from coarse to fine grained. Lamprophyres of two principal types, fine grained schistose and coarser grained non-schistose, both containing abundant biotite, are common.

Tentative age relationships of some of the granites and the dikes are as follows:-