Editing Arras (section)

===Geology===
The soil of Arras is primarily composed of [[chalk]], a soft, white, porous sedimentary rock that formed what is called the European stratigraphic unit. That [[Chalk Group]] deposited during the [[Late Cretaceous]] period 90&nbsp;million years ago. It used to be extracted to construct the most prestigious buildings and houses of Arras. As a result, residents once nicknamed the city ''La ville blanche'' (the White Town). The Arras area soil is also composed of [[clay]], which was used to produce bricks, build less noble buildings, and embellish façades. Clay is mostly found in the ''lieu-dit'' of ''La Terre Potier'' in the western part of the city.

The level of earthquake hazard in the Arras area is low, as it is in the whole Pas-de-Calais department.