<P> The Cordillera de Amambay merges with the Cordillera de Mbaracayú, which reaches eastward 120 kilometers (75 mi) to the Río Paraná . The average height of this mountain chain is 200 meters (656 ft); the highest point of the chain, 500 meters (1,640 ft), lies within Brazilian territory . The Río Paraná forms the Salto del Guairá waterfall where it cuts through the mountains of the Cordillera de Mbaracayú to enter Argentina . </P> <P> The Cordillera de Caaguazú falls where the other two main mountain ranges meet and extends south, with an average height of 400 meters (1,312 ft). Its highest point, Cerro de San Joaquín, reaches 500 meters (1,640 ft) above sea level . This chain is not a continuous massif but is interrupted by hills and undulations covered with forests and meadows . The Cordillera de Caaguazú reaches westward from the Paraná Plateau into the Central Hill Belt . </P> <P> A lesser mountain chain, the Serranía de Mbaracayú, also rises at the point where the Cordillera de Amambay and Cordillera de Mbaracayú meet . The Serranía de Mbaracayú extends east and then south to parallel the Río Paraná; the mountain chain has an average height of 500 meters (1,640 ft). </P> <P> Separated from the Eastern region by the Paraguay River, the Chaco region is a vast plain with elevations reaching no higher than 300 m (984 ft) and averaging 125 m (410 ft). Covering more than 60 percent of Paraguay's total land area, the Chaco plain slopes gently eastward to the Río Paraguay . </P>

What low-lying plain covers parts of argentina paraguay and bolivia