Structure
Folding and faulting apparently are absent in Vigan-Bantay Plain except in the eastern and southern margin of the plain. In the eastern margin, a north-south trending fault occurs transecting the Pre-Quarternary rocks. The fault line runs from Sinait down to Bantay and Santa, while the southern extension of the plain is bounded by another structural line that trends northwest and southeast occurring from Santa down to Narvacan and Santa Maria.
