Stirling Range
The Stirling Range or Koikyennuruff is a range of mountains and hills in the Great Southern region of Western Australia, 337 km south-east of Perth. It is located at approximately 34°24′S 118°09′E / 34.400°S 118.150°E and is over 60 km wide from west to east, stretching from the highway between Mount Barker and Cranbrook eastward past Gnowangerup. The Stirling Range is protected by the Stirling Range National Park, which was gazetted in 1913, and has an area of 1,159 km2.
The mountains are formed of metamorphic rock derived from sediments deposited during the Paleoproterozoic era, between 2.0 and 1.2 billion years old (based on U-Pb isotope geochronology). The sediments were subsequently metamorphosed to quartzites and shales 1.2 billion years ago, and later folded during reactivation of basement structures recording lateral displacements between Antarctica and Australia. Despite the relative youth of the mountains, the soils remain very poor, creating the species-rich heathland flora.
As the only vertical obstacle to weather in any direction, the range also tends to alter weather patterns around itself. Its upper slopes receive significantly more rainfall than surrounding areas. The branch of the Kalgan River, which forms the southwestern border of the park, is fed in large part from precipitation falling in the western half of the range.
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