The physiography of the municipality falls into two basic categories: an alluvial plain and a mountainous terrain. The central plain, where the Poblacion is located, has an elevation of about 100 meters above mean sea level, and is predominantly characterized by low relief and moderately sloping areas. Three fourths of the town is covered by these flatland which may be considered as a broad alluvial plain with recent depositions and residual soils. These areas are found sandwiched between the eastern and western uplands as well as on the other side of the Sierra Madre foothills.