- 2. Patagonian Molasse. Partly marine, partly terrestrial. Lower Miocene. Wilckens includes in this series the coal of Punta Arenas, and the marine beds below it.
- 3. Santa Cruz series. Containing remains of mammals. Middle and Upper Miocene.
- 4. Paraná series. Sandstones and conglomerates with marine fossils. Pliocene. Confined to the eastern part of the region.
The Upper Cretaceous and Tertiary deposits have revealed a most interesting vertebrate fauna. This, together with the discovery of the perfect cranium of a chelonian of the genus Alyolania, which may be said to be almost identical with Myolania oweni of the Pleistocene age in Queensland, forms an evident proof of the connexion between the Australian and South American continents. The Patagonian Myolania belongs to the Upper Chalk, having been found associated with remains of Dinosauria. Other specimens of the interesting fauna of Patagonia, belonging to the Middle Tertiary, are the gigantic wingless birds, exceeding in size any hitherto known, and the singular mammal Pyrotherium, also of very large dimensions. In the Tertiary marine formation a considerable number of cetaceans has been discovered. In deposits of much later date, formed when the physiognomy of the country did not differ materially from that of the present time, there have been discovered remains of pampean mammals, such as Glyptodon and Macrauchenia, and in a cave near Last Hope Inlet, a gigantic ground sloth (Grypotherium listai), an animal which lived contemporaneously with man, and whose skin, well preserved, showed that its extermination was undoubtedly very recent. With the remains of Grypotherium have been found those of the horse (Onoshippidium), which are known only from the lower pampas mud, and of the Arctotherium, which is found, although not in abundance, in even the most modern Pleistocene deposits in the pampas of Buenos Aires. It would not be surprising if this latter animal were still in existence, for footprints, which may be attributed to it, have been observed on the borders of the rivers Tamango and Pista, affluents of the Las Heras, which run through the eastern foot-hills of the Cordillera in 47° S.
Glaciers occupy the valleys of the main chain and some of the lateral ridges of the Cordillera, and descend to lakes San Martin, Viedma, Argentino and others in the same locality, strewing them with icebergs. In Patagonia an immense ice-sheet extended to the east of the present Atlantic coast during the first ice age, at the close of the Tertiary epoch, while, during the second glacial age in modern times, the terminal moraines have generally stopped, 30 miles in the north and 50 miles in the south, east of the summit of the Cordillera. These ice-sheets, which scooped out the greater part of the longitudinal depressions, and appear to have rapidly retreated to the point where the glaciers now e.st, did not, however, in their retirement fill up with their detritus the fjords of the Cordillera, for these are now occupied by deep lakes on the east, and on the west by the Pacific channels, some of which are as much as 250 fathoms in depth, and soundings taken in them show that the fjords are as usual deeper in the vicinity of the mountains than to the west of the islands. Several of the high peaks are still active volcanoes.
In so far as its main characteristics are concerned, Patagonia seems to be a portion of the Antarctic continent, the permanence of which dates from very recent times, as is evidenced by the apparent recent emergence of the islets around Chiloe, and by the general character of the pampean formation. Some of the promontories of Chiloe are still called huapi, the Araucanian equivalent for “islands”; and this may perhaps be accepted as perpetuating the recollection of the time when they actually were islands. They are composed of caps of shingle, with great, more or less rounded boulders, sand and volcanic ashes, precisely of the same form as occurs on the Patagonian plateau. From an examination of the pampean formation it is evident that in recent times the land of the province of Buenos Aires extended farther to the east, and that the advance of the sea, and the salt-water deposits left by it when it retired, forming some of the lowlands which occur on the littoral and in the interior of the pampas, are much more recent phenomena; and certain caps of shingle, derived from rocks of a different class from those of the neighbouring hills, which are observed on the Atlantic coasts of the same province, and increase in quantity and size towards the south, seem to indicate that the caps of shingle which now cover such a great part of the Patagonian territory recently extended farther to the east, over land which has now disappeared beneath the sea, while other marine deposits along the same coasts became converted into bays during the subsequent advance of the sea. There are besides, in the neighbourhood of the present coast, deposits of volcanic ashes, and the ocean throws up on its shores blocks of basaltic lava, which in all probability proceed from eruptions of submerged volcanoes now extinct. One fact, however, which apparently demonstrates with greater certainty the existence in recent times of land that is now lost, is the presence of remains of pampean mammals in Pleistocene deposits in the bay of San Julian and jn Santa Cruz. The animals undoubtedly reached these localities from the east; it is not at all probable that they advanced from the north southwards across the plateau intersected at that time by great rivers and covered by the ice-sheet. With the exception of the discoveries at the inlet of Ultima Esperanza, which is in close communication with the Atlantic valley of Gallegos, none of these remains have been discovered in the Andean regions.
On the upper plains of Neuquen territory thousands of cattle can be fed, and the forests around Lakes Traful and Nahuel-Huapi yield large quantities of valuable timber. The Neuquen river is not navigable, but as its waters are capable of being easily dammed in places, large stretches of land in its valley are utilized; but the lands on each side of its lower part are of little commercial value. As the Cordillera is approached the soil becomes more fertile, and suitable districts for the rearing of cattle and other agricultural purposes exist between the regions which surround the Tromen volcano and the first ridges of the Andes. Chos Malal, the capital of the territory, is situated in one of these valleys. More to the west is the mining region, in great part unexplored, but containing deposits of gold, silver, copper and lignite. In the centre of the territory, also in the neighbourhood of the mining districts, are the valleys of Norquin and Las Lajas, the general camp of the Argentine army in Patagonia, with excellent timber in the forest on the Andean slope. The wide valleys occur near Rio Malleco, Lake Huechulafquen, the river Chimehuin, and Vega de Chapelco, near Lake Lacar, where are situated villages of some importance, such as Junin de los Andes and San Martin de los Andes. Close to these are the famous apple orchards supposed to have been planted by the Jesuits in the 17th and 18th centuries. These regions are drained by the river Collon-Cura, the principal affluent of the river Limay. Lake Lacar is now a con tributary of the Pacific, its outlet having been changed to the west, owing to a passage having been opened through the Cordillera.
The Rio Negro runs along a wide transverse depression, the middle part of which is followed by the railway which runs to the settlement of Neuquen at the confluence of the rivers Limay and Neuquen. In this depression are several settlements, among them Viedma, the capital of the Rio Negro territory, Pringles, Conesa, Choele-Choel and Roca. To the south of the Rio Negro the Patagonian plateau is intersected by the depressions of the Gualicho and Maquinchau, which in former times directed the waters of two great rivers (now disappeared) to the gulf of San Matias, the first-named depression draining the network of the Collon-Cura and the second the Nahuel-Huapi lake system. In 42° S. there is a third broad transverse depression, apparently the bed of another great river, now perished, which carried to the Atlantic the waters of a portion of the eastern slope of the Andes, between 41° and 42° 30′ S.
Chubut territory presents the same characteristics as the Rio Negro territory. Rawson, the capital, is situated at the mouth of the river Chubut on the Atlantic (42° 30′ S.). The town was founded in 1865 by a group of colonists from Wales, assisted by the Argentine government; and its prosperity has led to the foundation of other important centres in the valley, such as Treleu and Gaiman, which is connected by railway with Porto Madrjm on Bahia Nueva. Here is the seat of the governor of the territory, and by 1895 the inhabitants of this part of the territory, composed principally of Argentines, Welsh and Italians, numbered 2585. The valley has been irrigated and cultivated, and produces the best wheat of the Argentine Republic. Between the Chubut and the Senguerr there are vast stretches of fertile land, spreading over the Andean region to the foot of the Cordillera and the lateral ridges of the Pre-Cordillera, and filling the basins of some desiccated lakes, which have been occupied since 1885, and farms and colonies founded upon them. The chief of these colonies is that of the 16th of October (16 de Octobre), formed in 1886, mainly by the inhabitants of Chubut colony, in the longitudinal valley which extends to the eastern foot of the Cordillera. Other rivers in this territory flow into the Pacific through breaches in the Cordillera, e.g. the upper affluents of the Fetaleufu, Palena and Rio Cisnes. The principal affluent of the Palena, the Carrenleufu, carries off the waters of Lake General Paz, situated on the eastern slope of the Cordillera. Rio Pico, an affluent of the same river, receives nearly the whole of the waters of the extensive undulating plain which lies between the Rio Teka and the Rio Senguerr to the east of the Cordillera, while the remainder are carried away by the affluents of Rio Jehua, viz., the Cherque, Omkel and Appeleg. This region contains auriferous drifts, but these, like the auriferous deposits, veins of galena and lignite in the mountains farther west which flank the Cordillera, have not been properly investigated. At Lake Fontana there are auriferous drifts and lignite deposits which abound in fossil plants of the Cretaceous age. The streams which form the rivers Mayo and Chalia join the tributaries of the Rio Aisen, which flows into the Pacific, watering in its course extensive and valuable districts where colonization has been initiated by Argentine settlers. Colonies have also been formed in the basin of Lakes Musters and Colhue; and on the coasts near the Atlantic, along Bahia Camarones and the Gulf of San Jorge, there are extensive farms.
The territory of Santa Cruz is arid along the Atlantic coast and in the central portion between 46° and 50° S. With the exception of certain valleys at Puerto Deseado (Port Desire) and in the transverse basins which occur as far south as Puerto San Julian, and which contain several cattle farms, few spots are capable of cultivation, the pastures being poor, water insufficient and salt lagunas fairly numerous. Puerto Deseado is the outlet for the produce of the Andean region situated between Lakes Buenos Aires and Pueyrredon.
