The board of supervisors shall provide for the appointment of a board of adjustment, and in the regulations and restrictions adopted pursuant to the authority of this chapter shall provide that the said board of adjustment may, in appropriate cases, and subject to appropriate conditions and safeguards, make special exceptions to the terms of the ordinances or regulations in harmony with its general purpose and intent and in accordance with the general or specific rules therein contained, and provide that any property owner aggrieved by the action of the board of supervisors in the adoption of such regulations and restrictions may petition the said board of adjustment direct to modify regulations and restrictions as applied to such property owners.
 The board of supervisors may provide for its review of variances granted by the board of adjustment before their effective date. The board of supervisors may remand a decision to grant a variance to the board of adjustment for further study. If remanded, the effective date of the variance is delayed for thirty days from the date of the remand.