I
In Classical architecture , a triangular gable crowning a portico or facade.
The pediment was the crowning feature of the Greek temple front. The pediment's triangular wall surface, or tympanum, was often decorated with sculpture. The Romans adapted the pediment as a purely decorative form to finish doors, windows, and niches, sometimes using a series of alternating triangular and segmentally curved pediments, a motif revived in the Italian High Renaissance. Baroque-era designers developed many varieties of broken, scrolled, and reverse-curved pediments.
II
In geology, any relatively flat surface of bedrock (exposed or lightly covered with soil or gravel) that occurs at the base of a mountain or as a plain having no associated mountain.
Pediments are most conspicuous in basin-and-range-type desert areas throughout the world, but they also occur in humid areas. In the tropics, the surfaces tend to be covered with soil and obscured by vegetation. Many tropical river towns are situated on pediments, which offer easier building sites than the steep hillsides above or the river marshes below.