Final answer:
The Pampas is the name of the plains in Argentina and Uruguay, known for their fertile soil and grasslands, supporting a robust agricultural industry.
Step-by-step explanation:
The plains containing grassland and fertile soil located in Argentina and Uruguay are known as the Pampas. This region is characterized by its temperate, semi-arid climate and excellent soil quality, making it suitable for agriculture. The Pampas region is a vital agricultural area and includes the capital city of Buenos Aires, which holds about one-third of Argentina's population. It is celebrated for its extensive agricultural production, from cattle ranching in the western grasslands to diverse farming operations, which contribute significantly to making it the breadbasket of the Southern Cone.