An andesitic-to-dacitic stratovolcano complex in the Leonard Range is truncated by a 4 x 5 km caldera partially filled by Lake Leonard. The Leonard Kniazeff stratovolcano is located east of the head of Davao Gulf in SE Mindanao, east of the major N-S-trending Philippine Fault. Activity in the Leonard Range dates back to 1.1 million years. A dome building stage began about 290,000 years ago, producing a series of lava domes in the region surrounding Lake Leonard. A younger stage involved the eruption of the Paloc pyroclastic deposits from the late-Pleistocene to Holocene and the formation of the caldera. Radiocarbon dates ranging from about 6,000 to 1,800 years ago were obtained from the Paloc pyroclastic deposits. The Manat thermal area is located north of Lake Leonard, solfataras occur its SW rim, and active solfataras, fumaroles, and hot springs are found in the Amacan-Gopod thermal area south of the lake.