[1] Like the Pampas in general, the region's terrain is predominantly hilly and of a temperate climate, though rich mollisols are more abundant here than to the west, where soils of loessic origin are more common.

Except for a few bluffs near the Paraná and Río de la Plata rivers, as well as the Tandilia and Ventania mountain ranges to the south, the region's slope rarely exceeds 6 degrees.

The Uruguayan savanna, which lies east of the rivers in Entre Ríos Province of Argentina, Uruguay and the south of Brazil, is sometimes considered part of the Humid Pampa.

The natural vegetation comprises meadows of high grass with isolated forests (locally referred to as montes) of algarrobos, talas and chanares, which used to be common in areas near the main rivers but have been mostly cut down during the 20th century.

Being fertile and close to the Atlantic Ocean, the Humid Pampa was one of the preferred destinations of millions of immigrants, who were mostly Italian, French and Spanish, but also German and other Europeans.

The urban population of Argentina (89% of its 38.6 million inhabitants, as estimated for 2005) is concentrated today in cities within the Humid Pampa (Buenos Aires, Córdoba and Rosario are the largest).