Mount Warning, a mountain in the Tweed Range in the Northern Rivers region of New South Wales, Australia, was formed from a volcanic plug of the now-gone Tweed Volcano. The mountain is located 14 kilometres west-south-west of Murwillumbah, near the border between New South Wales and Queensland. Lieutenant James Cook saw the mountain fr…Mount Warning, a mountain in the Tweed Range in the Northern Rivers region of New South Wales, Australia, was formed from a volcanic plug of the now-gone Tweed Volcano. The mountain is located 14 kilometres west-south-west of Murwillumbah, near the border between New South Wales and Queensland. Lieutenant James Cook saw the mountain from the sea and named it Mount Warning.