West of the confluence of the Neuquen and the Limay the railway ascends the sandstone tableland, from 1,700 to 3,000 feet high, and goes as far as the foot of the first sub-Andean chain, the Zapala ranch. The eruptive rocks here have thrown up the sandstone, and the profiles raised north and south of Zapala, across the Sierra de la Vaca Muerta and the Cerro Lotena, cut through folds of Mesozoic strata which have been reduced by erosion to the level of the plateau. One already feels the vicinity of the Cordillera. Pasture is plentiful, the mallin is thick, and springs abound. The sheep-area stretches westward of Zapala, as far as the Rio Cataluin and the Rio Agrio. East of Zapala, on the other hand, the desolate condition of the country gets worse and worse. The supplies of water dry up in the summer, and the entire zone that lies east of 70° W. long. is useless, on account of the lack of permanent water, except as winter commonage. Hence, transhumation is here indispensable. It has been practised for a long time on the Chilean slope of the Cordillera from the latitude of Coquimbo and San Juan to the north of Lake Quillen. At present it tends to disappear from the Andes of the Neuquen.[75] But there is still transhumation on the Argentine side. The sheep of the plateau, driven from their winter pasture when the water dries up, ascend the Cordillera. Sometimes the mountains are not yet free from snow. In that case the journey is delayed, and the sheep feed on the way, to the great detriment of the land they cross.
There are many routes, and frequently they coincide with those which were formerly taken by the cattle of the Pampas in ascending to the passes of the Cordillera. Groeber mentions a transhumation track south of the Rio Barrancas and Lake Carri Lauquen. From the left bank of the Neuquen the flocks ascend by Chosmalal and Butamallin to the pasture of the Pichachen pass, or by Las Lajas to the Pino Hachado pass. From Zapala and the tableland further south they go to spend the summer in the Cataluin Cordillera, where the number of sheep in summer is calculated to be 70,000. Others go still further, to the source of the Alumine and the Arco pass. The volcano Lanin almost marks the southern limit of the zone of transhumation. The chief group of migrating sheep comes from the district of the Coyunco, the Cañadon Grande, and the Picun Leucu.
Transhumation is practised only by the intrusos. They go from the unowned lands of the tableland to the unowned lands of the Cordillera. The renting of winter pasture to owners is quite exceptional. The concessions of land granted by the Argentine Government are steadily reducing the area of the migrators in the Cordillera, and also the ways of communication between the tableland and the mountains. The proprietors do not care to receive the migrating flocks, and they put obstacles in their way by enclosing the land. The routes of the transhumation are now fixed by the spaces which remain open between the enclosed ranches. Moreover, the migrating intrusos are haunted by the fear of finding the winter pasture occupied by others during their absence, and they have no proprietary title. The splitting up of the land and the organization of ownership will before long lead to the extinction of the practice of transhumation, and the greater part of the winter pasturage will be turned into permanent pasture by boring wells and nursing the water-supply.
The district round the Zapala ranch has become very busy since the construction of the railway, which has deeply affected the conditions of life there. It has made a sort of capital of Zapala. It is curious to contrast the renaissance which has followed upon the appearance of the railway in this district with the much less material changes which it has made at Maquinchao. The life which the railway concentrates at Zapala includes not only the wool trade, as at Maquinchao, but also the cattle trade. The herds which are to be exported gather round the ranch at the same time as the tropas of wagons, and a good price is paid for the right of pasturage. While the Maquinchao line ends at the port of San Antonio, which is merely fitted up for the export of wool, the Zapala railway feeds the refrigerator at Bahía Blanca. It joins up with the network of railways of the Pampa. Sheep arrive at Zapala, not only from the surrounding district and from the Neuquen, but from a good part of the Rio Negro, and even the Chubut. The convoys of animals coming from the south find it best to keep near the Cordillera, where the pasturage is better. Only a few of them descend the Limay as far as Senillosa. From Zapala to Senillosa there is no suitable road in connection with the railway, and further east it is necessary to go as far as Choele Choel to find tracks which lead to it. The exporting of the sheep lasts five months, from November to March.
Zapala station is also a point of convergence of herds of cattle. There are people at Zapala who still remember the time when the cattle brought from the Pampa to go to Chile passed through their valley. Although these exports of Pampean cattle to Chile ceased after 1885, the whole Andean region of the Neuquen still lived entirely on the Chilean market until very recently. The attraction of the Chilean market is one of the reasons for the survival of transhumation. It was to the advantage of the Argentine breeders to keep near the Cordillera and the passes through which the buyers came from Chile in the summer. The life of the small centres in the upper valleys which developed rapidly after the conquest (Chosmalal, Ñorquin, Codihue, Junin, and San Martin) was bound up with the Chilean cattle trade, and was reflected on the opposite side of the Andes in the prosperity of the corresponding markets in Chile.
In the years immediately preceding 1914, a sudden revolution upset the cattle traffic on the Neuquen, and the attraction of Buenos Aires took the place of that of the Chilean market. The commercial influence of Buenos Aires was first felt in the wool-market. The tropas of wagons which brought wool to Zapala loaded up, in exchange, with the flour and salt that were needed for sheep-breeding in the pastures of the Cordillera (pastos dulces). The import trade followed the path traced by the export trade. The small Chilean wagons which still cross the Cordillera now only bring to the Neuquen the coarse flour of Chile, haricot beans, and wine. They return empty to Chile. After the wool-buyers, the cattle-merchants of Buenos Aires next found their way to the Cordillera. The centres where the sales of cattle for Chile used to be held are now in decay, and have lost part of their population. The cattle are sent to the fattening centres on the Pampa, or to the Bahía Blanca and Buenos Aires markets. Thus we have under our eyes, unexpectedly, in the north of Patagonia a transformation that occurred gradually half a century ago in all the western and north-western parts of Argentina. In its many forms it is the essential fact in the modern history of Argentine colonization. The more distant provinces are detached in succession from foreign markets, and the whole national life is being organized round the great economic focus which the region of the Pampas has become.