Un caos de bloques, caos de bolas o ***berrocal*** es un tipo de paisaje granítico,​ en el que se presenta una gran cantidad de berruecos, bolones o piedras caballeras.
http://es.wikipedia.org/wiki/Caos_de_bloques

This links to the English page
http://en.wikipedia.org/wiki/Spheroidal_weathering
Spheroidal weathering is a form of chemical weathering that affects jointed bedrock and results in the formation of concentric or spherical layers of highly decayed rock within weathered bedrock that is known as **saprolite**.


Saprolite is a chemically weathered rock. Saprolites form in the lower zones of soil profiles and represent deep weathering of the bedrock surface.
http://en.wikipedia.org/wiki/Saprolite

If you want to avoid technical jargon, you could just say "berrocal (heavily weathered rock)".

https://dle.rae.es/berrocal ?m=form
https://dle.rae.es/berrueco#2L9IeCY
https://www.wordreference.com/es/en/translation.asp?spen=ber...
https://www.google.com/search?q=corestone&rlz=1C1SQJL_esES95...

Spanish term (edited): barrocal

I suggest you leave the name in Portuguese, and explain what and where it is.

Barrocal means exactly clay (barro, in Portuguese and Spanish) and lime (cal,
idem). It means, in real terms, a fine layer of clayish soil –mostly 10 to 20 cm of clay over an extensive mass of lime rock. In the past, a karstic process took place forming big aquifers with various depths, normally reaching hundreds of meters [2].

Barrocal
A natural sub-region of the Algarve, located between the Serra and the Coast. In geological terms, it is characterized by the presence of several calcareous elevations of irregular form, that rarely exceed the 400 meters of altitude, denominated baroque. This subregion crosses the Algarve longitudinally, the central region being wider than the extremities. In its endemic vegetation the holm oak forests predominate. However, man's continued action has given rise to a more degraded vegetation cover where shrubs such as the zambujeiro or myrtle, small carob trees and a few specimens isolated from holm oak predominate. In agricultural terms, rainforest crops predominated over the centuries, especially the almond, fig, carob and olive trees. In the valleys prevailed the cultures of irrigated, especially of citrinos. In the last decades we have seen the expansion of irrigated and vineyard crops to areas formerly occupied by the dry land. At present agricultural production is largely abandoned.

https://sapientia.ualg.pt/bitstream/10400.1/10342/1/Paper mu...

https://educalingo.com/en/dic-pt/barrocal