Geology - Soil & Rocks
The history of the Styx River is closely related to the formation of the Canterbury Plains.
In earlier times the flow of the Styx River would have been provided by a combination of spring water and channels connecting with the Waimakariri River.
There is a strip of very young soils along the middle reaches of the Styx River and Smacks Creek that suggest a recent connection between the two river systems.
Today the Styx River consists of a low-gradient, narrow, meandering, single-thread channel that is incised into a fan surface largely formed by sedimentation from the Waimakariri River.
The springs that feed the Styx River ecosystem mainly occur along a line that is close to the western limit of the surface confining layer of fine-grained sediment overlying gravel, and probably indicate the presence of gravel channels within the Springston or Christchurch Formation.