The Wolds is a term used in England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 to describe a range of hills which consists of open country overlying a base of limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 or chalk

Chalk

Chalk is a soft, white, porous sedimentary rock, a form of limestone composed of the mineral calcite. Calcite is calcium carbonate or CaCO3. It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite plates shed from micro-organisms called coccolithophores....

. There are at least two such areas, both remnants of a much larger chalk system. They are geologically a single range but are physically separated by the Humber Estuary.

See:

• Lincolnshire Wolds
  Lincolnshire Wolds
  The Lincolnshire Wolds is a range of hills in the county of Lincolnshire, England. It is a designated Area of Outstanding Natural Beauty , and the highest area of land in eastern England between Yorkshire and Kent...
  
  
• Yorkshire Wolds
  Yorkshire Wolds
  The Yorkshire Wolds are low hills in the counties of East Riding of Yorkshire and North Yorkshire in northeastern England. The name also applies to the district in which the hills lie....
  
  

In addition there are the Cotswolds

Cotswolds

The Cotswolds are a range of hills in west-central England, sometimes called the Heart of England, an area across and long. The area has been designated as the Cotswold Area of Outstanding Natural Beauty...

, which are a range of limestone hills in the South West of England.