Singapore Island (the main island, Pulau Ujong) is primarily a product of ancient volcanic activity and sedimentary processes, followed by extensive modern land reclamation. Geologically, the island's "core" is made of the Bukit Timah Granite, which was formed by volcanic eruptions roughly 200 million years ago during the Triassic period. Over millions of years, this volcanic base was covered by layers of sedimentary rock, known as the Jurong Formation, created by the accumulation of sand and mud in a prehistoric marine environment. In more recent geological time, the island's current shape was defined by rising and falling sea levels after the last ice age. However, the Singapore we see today is also a product of "human-made" formation; since the early 19th century, Singapore has increased its total land area by approximately 25% through land reclamation. Using sand imported from neighboring countries and earth from its own hills, the country has physically expanded its coastline, connecting smaller islands and creating entire new districts like Jurong Island and Marina Bay. This combination of ancient igneous rock and modern engineering makes Singapore's formation a unique story of both tectonic history and massive human intervention to overcome the limitations of a small island nation.