It's possible that he's saying a tunnel already existed. My reason for asking is the connection between gold and Indonesia.
" "Warrandyte" translated as "that which is thrown". Bunjil, the great eagle, the all-powerful, ever-watchful creator of the world, had once gazed down upon his people from the Star Altair and seen their wrongdoing. Awaiting their return, with a mighty crash of thunder, he hurled down a star to destroy them. Where star struck created the gorge we see today. Bunjil's people always remembered the spot. They called it Warrandyte, .."
Source: Warrandyte Diary.
Aboriginal words - 'Warren' meaning 'to throw' and 'dyte' meaning 'the thing thrown at" ... Bunjil threw down the star'.
Joy Braybrook - 2012 - History
Warrandyte: The word meaning, 'Where the star was thrown'.
East Melbourne dyte . North Melbourne duta '"star" , north Vic. durt "star".
Old Java language 800-1300 CE. dyuh (Skt dyu-, heaven)
dyuti (cf Skt jyotis) heavenly bodies .
wara (Skt) act or object of choosing, most excellent among. (wara-ne possessive : "star of choosing").
wraa (Skt wraa, warding off, resisting).
wara* waraan a part. colour? (yellowish? reddish?).
" . the first recognised Gold Field in Victoria in 1851, at Andersons Creek near Warrandyte". ( were nuggets seen as the remnants of the star?).
"In the puranas, the Sudarshana Chakra was made by the architect of gods, Vishvakarma. Vishvakarma's daughter Sanjana was married to Surya. Due to the Sun's blazing light and heat, she could not go near the Sun. She complained to her father about this. Vishvakarma made the sun shine less so that his daughter could hug the Sun. The left over stardust was collected by Vishvakarma and made into Sudarshana Chakra of Vishnu. The Chakra is described to have 10 million spikes in two rows moving in opposite directions to give it a serrated edge.
Sudarshana Chakra was used to cut the corpse of Sati, the consort of Shiva into 51 pieces after she gave up her life by throwing herself in a yagna (fire sacrifice) of her father Daksha. Shiva, in grief, carried around her lifeless body and was inconsolable. The 51 parts of the goddess' body were then tossed about in different parts of the Indian subcontinent and became "Shakti Peethas".
According to the Ahirbudhanya Samhita, "Vishnu, in the form of Chakra, was held as the ideal of worship for kings desirous of obtaining universal sovereignty" .
"The Chakri dynasty is the current ruling royal house of the Kingdom of Thailand, since 1782 Prior to the founding of the dynasty, King Rama I held for years the title Chakri,.The emblem of the dynasty is composed of the discus (Chakra) and the trident (Trisula), the celestial weapons of god Vishnu and Shiva, whom the Thai sovereign is seen as an incarnation."
Vishnu with a chakra weapon rode Garuda eagle , identified with Aquila "eagle" stars of Altair, as is Bunjil the eagle-man.