Here's why:
* Fold mountains form when layers of rock are compressed and folded upwards, like the Himalayas.
* Fault mountains form when blocks of rock are uplifted along faults, like the Sierra Nevada.
* Plateau mountains are formed by erosion of a plateau, leaving behind isolated peaks.
Mount Kosciuszko is part of the Australian Alps, which are a plateau that has been eroded over millions of years. This erosion has left behind the highest peaks, including Mount Kosciuszko.
