Gerona has a land area of 12,889 hectares (31,850 acres) of plain and rugged agricultural land representing 4.63% of the province total area. The Tarlac River, which originates from the eastern slopes of the Zambales Mountain, cuts across the west central areas, dividing the town into two parts.
The eastern area consists of 31 barangays with total land area of 90.50 square kilometres representing 63.9% of the total area. It is characterized as plain, low-lying agricultural land.
The second part is the Western Area consisting of 13 barangays with total area of 50.97 square kilometres representing 36.03% of the total land area. It is characterized by hilly and rugged agricultural land and is also forested.
1894 Saint Catherine of Alexandria Church of Gerona  (Vicariate of St. Catherine of Alexandria, Vicar Forane: Father Alfredo Dizon, Titular: Saint Catherine of Alexandria, Feast day, November 24 Parish Priest: Father Alfredo Dizon, succeeded by Fr. Ramon Capuno  Parochial Vicar: Rev. Fr. Paulo Dela Cruz  - Don Federico Bartolome Street, McArthur Highway, Gerona, Tarlac 2302, Philippines  under the Roman Catholic Diocese of TarlacRoman Catholic Diocese of Tarlac led by Most Rev. Florentino F. Cinense, D.D., PhD, STL.