ABSTRACT
The Spanish Central System is a hard rock (igneous and metamorphic) range bounded by faults. It is located in the middle of the Iberian Peninsula. Igneous and metamorphic rocks are normally poor aquifers, with low salinity and calcium-bicarbonate type groundwater. There are a few springs and wells with a different chemical composition that reflect deeper groundwater flow paths. Around these points Spiny rush bushes are found, a bioindicator of salty and/or alkaline soils but so far only described in soils formed over detrital formations. Thus, the presence of Spiny rush can be an indicator for the location of deep groundwater flows into hard rocks.
