The Great Barrier Reef was formed through millions of years of coral growth combined with geological and environmental changes. It sits on a coastal plain made up of sediments from the Great Dividing Range mountains, which were once continental islands. As the last ice age ended about 6,000 to 8,000 years ago, rising sea levels flooded the area, creating shallow, nutrient-rich waters ideal for coral growth. Coral polyps, tiny organisms, attached themselves to rocks and secreted calcium carbonate to build the reef structure. Over thousands of years, coral growth continued, extending upward and outward as the mountains submerged, forming the reef system and small islands we see today. The reef continues to evolve and grow in warm waters with optimal temperatures between 21°C and 29°C.
Key factors in the formation include:
- The reef's foundation is sediments from the Great Dividing Range.
- Coral polyps started the reef by attaching to submerged landforms.
- Sea level changes post-ice age flooded the coastal plain.
- Coral secretion of calcium carbonate created the reef structure.
- Geological processes like subsidence and continental drift influenced development.
- The reef is estimated to be about 6,000 to 8,000 years old, though coral growth in the area dates back millions of years.
