It is implied from rocks called banded iron formations, many of which can be observed as hundreds-of-meter-thick packages of rock which are exposed in gorges that carve their way through the Karijini National Park in Western Australia.

从称为带状铁层的岩石中可以看出这一点，其中许多可以观察到数百米厚的岩石包， 这些岩石暴露在穿过西澳大利亚卡里吉尼国家公园的峡谷中。