RODNEY Cordilleras. It is not certainly known whether any of them are volcanic. Pumice stones are often seen floating on the Mississippi, and still oftener on the Missouri. These are generally of a reddish yellow, or flame colour, and are amongst the largest and finest specimens of this substance to be met with. Some assert that they proceed from hills of burning coal, but we never heard of hills of burning coal ever yielding such a product. They are entirely a volcanic production, and beyond doubt are either discharged from craters at present active, or are washed away by the mountain torrents, from places which were formerly the scene of such phenomena. Mica is also abundantly carried along by the waters which flow from the Rocky Mountains. The great rivers that are discharged from their eastern and western declivities wind among the mountains, the Arkansas on the east, and the Oregon or Columbia on the west, more than a hundred leagues before they issue into the plains. In following the beds of such streams, travellers pass through the range without much difficulty, so that the reports of the early travellers that they presented a high, continuous, and almost impassable barrier, are incorrect. Various leaders of expeditions have passed them at different points, and affirm that they found no such formidable and insurmountable barriers, the mention of which was wont to deter traders from attempting to cross from east to west or from west to east by this route. Following the river Platt, which is one of the principal southern branches of the Missouri, the traveller finds a road even to Lake Buenaventura, on the Pacific plains, that needs little labour to adapt it to the passage of horses and waggons. The acclivity is nowhere so great as to exceed an ascent of three degrees.
This vast range has been divided into the Rocky, Chey-wan, and Masserne Mountains, on what ground is not exactly known. The ranges on the south, at the sources of the Arkansas, and running thence towards the Gulf of Mexico, are called the Masserne Mountains. A single peak of this ridge, seen as a landmark for immense distances over the subjacent plains, is called Mount Pike, a very appropriate name. It is described as of incomparable grandeur in appearance, and has been differently estimated at from seven to ten thousand feet in height. On the ridges of the Rocky Mountains, the Colorado of the Pacific, the Rio del Norte of Mexico, the Roche-jaune or Yellow-stone of the Missouri, and the Arkansas and Red River of the Mississippi, streams which have outlets at such immense distances apart, all have their origin. Many accounts have been given of the appearance of silver and other metals in the Rocky Mountains, but they have been too partially explored to entitle us to pronounce on the extent or value of the veins.