[37] The latitude of the Great Salt Lake was taken from about the centre of the north side of it, where the party were encamped. In 1786 Don Pablo Zisur, a lieutenant in the Spanish navy, had fixed the north-east angle of the lake in lat. 37° 10´, and 4° 36´ west of the meridian of Luxan (Guardia); according to him the lake of Cabeza del Buey is in lat. 36° 8´, and the Guardia de Luxan in 34° 36´. Azara fixed it in 34° 38´ 36". [38] In the life of the _Carreras_, given in the Appendix to Mrs. Graham's account of Chile, there is an account of some of these Indian forays in conjunction with Carrera's troops, particularly of their surprisal of the town of Salto, and the carrying off from thence of 250 women and children, after butchering all the men, in spite of every effort of their unnatural allies to prevent it. [39] Villariño found the Indians in the Cordillera opposite to Valdivia calling themselves Aucases. [40] Garcia seems to have believed that the language and origin of this people was different from the other Indians he fell in with. There is no proof, however, adduced of the difference of language, and I suspect they were only a further-removed branch of the Araucanian family, as were the Indians Viedma found at San Julian's in 1782. [41] Captain Fitzroy determined it to be 3350 feet _above the level of the sea_, from which its true distance is 45 miles. [42] At Buenos Ayres the variation in 1708 was 16° 45´ east; in 1789 it was 16° 30´; and in 1818 it was 12-1/2 east. [43] A collection of the birds of those regions would form a most interesting addition to any museum. A large proportion of them are, I believe, quite unknown in Europe. [44] An accident to the barometer prevented the officers making a series of observations with that instrument, which would have been of considerable interest. They made, however, good use of the thermometer, of which a daily register was preserved. [45] I understand, however, that General Ramos has expressed his opinion that it is not navigable for more than _forty leagues_ from its mouth. CHAPTER X. GEOLOGY OF THE PAMPAS. Geological Features of the Southern compared with those of the Northern Shore of the Plata. The Pampa Formation, probably derived from the Alluvial Process now going on, as exhibited in the Beds of the Plata itself and other Rivers. Fossil remains of land Animals found in it, above Marine Shells. Such Shells where met with, and of what Species. Mr. Bland's Theory of the Upheaval of the Pampas from the Sea, founded on the Deposits of Salt in them:--The presence of such Salt may be otherwise accounted for. Account of the Discovery of the Gigantic Fossil remains sent to England by the Author.