Remnant of sedimentary mudstone strata overlooking Porcupine Gorge in Porcupine Gorge National Park at the headwaters of the Flinders River, southern Gulf of Carpentaria, Queensland, Australia. The waters of Porcupine Creek have eroded through a Tertiary basalt cap and successive beds of mudstone, conglomerate and sandstone spanning 500 million years, including sediments of a Mesozoic inland sea covering north Queensland in which some of the most complete fossilized dinosaur and pliosaur skeletons in the world have been found.