The position of the area described here as the 'Headwaters of the Burke River in the tropical zone of Australia is evident from the locality map, Figure 1. Topographically it is part of the Selwyn Range, which is a divide composed mainly of metamorphosed Precambrian rocks. These are described by Carter (1959), Carter & Brooks (1960), and Carter, Brooks, & Walker (1961). Structurally it is part of the Burke River Outlier, within which the Selwyn Range is built of Cambrian sediments, which are referred to as 'the Selwyn Range sequence'. This sequence is preserved here owing to post. Cambrian faulting that involves the whole Outlier; the Outlier itself is the northern segment of the Burke River Structural Belt, which extends south for another hundred miles. The headwaters of the Burke River are in the Selwyn Range, north-western Queensland. Exploration began in 1860; Cambrian fossils were discovered in 1931. Mapping by the Commonwealth Bureau of Mineral Resources (1952-1958) amplified the knowledge of the geology and palaeontology of the area. Four formations (Roaring Siltstone, Devoncourt Limestone, Selwyn Range Limestone, and O'Hara Shale) and one unit of beds (Mount Birnie Beds) constitute the Cambrian of the Selwyn Range sequence. The Mount Birnie Beds (sandstone, arkose, regolithic clay) occurs as erosional residuals on the basement. Unconformably above follows the Roaring Siltstone with shale and sandstone interbeds; above it rests the Devoncourt Limestone, flaggy and bituminous; the next higher is the Selwyn Range Limestone, a caIcilutite with chert and marly interbeds, overlain by the O'Hara Shale with interbeds of chert and sandstone. A Mesozoic conglomerate (erosional residuals) and alluvial deposits conclude the sequence.The position of the area described here as the 'Headwaters of the Burke River in the tropical zone of Australia is evident from the locality map, Figure 1. Topographically it is part of the Selwyn Range, which is a divide composed mainly of metamorphosed Precambrian rocks. These are described by Carter (1959), Carter & Brooks (1960), and Carter, Brooks, & Walker (1961). Structurally it is part of the Burke River Outlier, within which the Selwyn Range is built of Cambrian sediments, which are referred to as 'the Selwyn Range sequence'. This sequence is preserved here owing to post. Cambrian faulting that involves the whole Outlier; the Outlier itself is the northern segment of the Burke River Structural Belt, which extends south for another hundred miles. The headwaters of the Burke River are in the Selwyn Range, north-western Queensland. Exploration began in 1860; Cambrian fossils were discovered in 1931. Mapping by the Commonwealth Bureau of Mineral Resources (1952-1958) amplified the knowledge of the geology and palaeontology of the area. Four formations (Roaring Siltstone, Devoncourt Limestone, Selwyn Range Limestone, and O'Hara Shale) and one unit of beds (Mount Birnie Beds) constitute the Cambrian of the Selwyn Range sequence. The Mount Birnie Beds (sandstone, arkose, regolithic clay) occurs as erosional residuals on the basement. Unconformably above follows the Roaring Siltstone with shale and sandstone interbeds; above it rests the Devoncourt Limestone, flaggy and bituminous; the next higher is the Selwyn Range Limestone, a caIcilutite with chert and marly interbeds, overlain by the O'Hara Shale with interbeds of chert and sandstone. A Mesozoic conglomerate (erosional residuals) and alluvial deposits conclude the sequence.