Editing Cambrai (section)

===Geology and landforms===
[[File:NPdC relief Cambrai.png|thumb|right|Cambrai in its topographical context]]

Cambrai is located on [[chalk]] bedrock of the [[Cretaceous]] period{{cn|date=June 2024}}, which forms the northern boundary of the [[Paris Basin]], between, to the east, the hills for [[Thiérache]] and [[Arrondissement of Avesnes-sur-Helpe|Avesnois]], the foothills of the {{Interlanguage link multi|Massif ardennais|fr|3=Massif ardennais|lt=Ardennes}}, and northwest, the hills of [[Artois]]. It is at a point which is relatively lower than these two regions, called the "Cambrai threshold" or the "Bapaume threshold", which facilitates the passage between the south and the north: Bapaume (Artois) is {{convert|100|m|ft}} above sea level, [[Avesnes-sur-Helpe]] (Avesnois) is at {{convert|143|m|ft}} and Cambrai only {{convert|41|m|ft}}. The [[Canal de Saint-Quentin|Saint-Quentin canal]], the [[Canal du Nord]], the [[A1 autoroute (France)|A1]], [[A2 autoroute (France)|A2]] and [[A26 autoroute|A26]] autoroutes all borrow all this passage between the basin of the [[Seine]] and the plains of the Nord department.

The chalky subsoil allowed, as in many medieval cities, the digging of a network of cellars, tunnels and quarries under the city. The poor quality of the Cambrai chalk was reserved for use in the manufacture of lime or filling, as well as common constructions. For prestigious buildings, stone from the nearby villages of [[Noyelles-sur-Escaut]], [[Rumilly-en-Cambrésis|Rumilly]] or [[Marcoing]] was used.<ref group="a" name="p.37">p.37</ref>

The city is bordered in its western part, as well as to the north and the south, by the alluvial zones of the Scheldt Valley.