The rock observed on the shore at Coen River, the only point on the eastern side of the Gulf where Captain Flinders landed, was calcareous sandstone of recent concretional formation.
(*Footnote.

Flinders Charts Plate 14.) (**Footnote.

Flinders Volume 2 page 158.) In Sweer's Island, one of Wellesley's Isles, a hill of about fifty or sixty feet in height was covered with a sandy calcareous stone, having the appearance of concretions rising irregularly about a foot above the general surface, without any distinct ramifications.

The specimens from this place have evidently the structure of stalactites, which seem to have been formed in sand; and the reddish carbonate of lime, by which the sand has been agglutinated, is of the same character with that of the west coast, where a similar concreted limestone occurs in great abundance.
The western shore of the Gulf of Carpentaria is somewhat higher, and from Limmen's Bight to the latitude of Groote Eylandt, is lined by a range of low hills.

On the north of the latter place, the coast becomes irregular and broken; the base of the country apparently consisting of primitive rocks, and the upper part of the hills of a reddish sandstone; some of the specimens of which are identical with that which occurs at Goulburn and Sims Islands on the north coast, and is very widely distributed on the north-west.