A great historical interest is attached to this part of the highland, especially to the neighbourhood of the Lake of Timpanogos, which is probably identical with the Lake of Teguayo, the ancestral seat of the Aztecs. This people, in their migration from Aztlan to Tula, and to the valley of Tenochtitlan in Mexico, made three stations at which the ruins of _Casas grandes_ are still to be seen. The first halting-place of the Aztecs was at the Lake of Teguayo, south of Quivira, the second on the Rio Gila, and the third not far from the Presidio de Llanos. Lieutenant Abert found on the banks of the Rio Gila the same immense quantity of elegantly painted fragments of delf and pottery scattered over a large surface of country, which, at the same place, had excited so much astonishment in the missionaries Francisco Garces and Pedro Fonte. From these products of the hand of man, it may be inferred that there was a time when a higher human civilization existed in this now desolate region. Repetitions of the singular architectural style of the Aztecs, and of their houses of seven stories, are at the present time to be found far to the east of the Rio Grande del Norte; as, for instance, at Taos.[IZ] The Sierra Nevada of California is parallel to the coast of the Pacific; but between the latitudes of 34° and 41°, between San Buenaventura and the Bay of Trinidad, there runs, west of the Sierra Nevada, a small coast chain whose culminating point, _Monte del Diablo_, is 3674 feet high. In the narrow valley, between this coast chain and the great Sierra Nevada, flow from the south the Rio de San Joaquin, and from the north the Rio del Sacramento. It is in the alluvial soil on the banks of the latter river that the rich goldwashings occur, which are now proceeding with so much activity. Besides the hypsometric levelling and the barometric measurements to which I have already referred (see page 33), between the mouth of the Kanzas River in the Missouri and the coast of the Pacific, throughout the immense expanse of 28° of longitude, Dr. Wislizenus has successfully prosecuted the levelling commenced by myself in the equinoctial zone of Mexico, to the north as far as to lat. 35° 38′, and consequently to Santa Fé del Nuevo Mexico. We learn with astonishment that the plateau which forms the broad crest of the Mexican Andes by no means sinks down to an inconsiderable height, as was long supposed to be the case. I give here, for the first time, according to recent measurements, the line of levelling from the city of Mexico to Santa Fé, which is within 16 miles from the Rio del Norte.