Geological Report of the Exploration of the Yellowstone and Missouri Rivers - 1859-'60 #261336

Nothing very definite was ascertained, however, respecting the geology of the country by this expedition, except to confirm the fact of the existence Of a cretaceous formation on the upper Missouri, indications Of which had already been determined from the collections of Lewis and Clarke. He also Obtained a fine specimen of the remains Of a saurian animal, characterizing the cretaceous period which was described by Goldfuss as Mosasaurus Maximilian, fragments of which were in the collection Of Lewis and Clarke. The next important expedition into that country was made in 1839, by the distinguished geographer Nicollet. He ascended the Missouri no farther than Fort Pierre, in latitude 440 yet from his Observations the first reliable information was obtained in regard to the extent and interest of the cretaceous rocks in that region. He collected a good many cretaceous fossils at different points along the river, especially at the Great Bend, all Of which were described by Conrad and Morton in the Proceedings of the Academy of Natural Sciences Of Philadelphia.