The general character of the land is undulating hills, with a few forest areas along the banks of the numerous streams. Southern Uruguay consists mostly of rolling plains and is an eastward extension of the Argentine pampas. The Atlantic coastline is fringed with tidal lakes and sand dunes. Low, unbroken stretches of level land line the banks of the two border rivers, the Uruguay and the Plata. The northern section is broken by occasional ridges and low ranges (cuchillas), alternating with broad valleys, and is a southern extension of Brazil. The highest point in the country, Catedral, is 514 m (1,686 ft) above sea level. The most noteworthy feature of the northwest landscape is the Cuchilla de Haedo. The Cuchilla Grande runs northeastward from the southern region to the Brazilian border. The Negro, which rises in Brazil, crosses Uruguayan territory and flows into the Uruguay River, which separates Uruguay from Argentina.