F.J. Pearson D. B. Smith R.A. Downing 1979 <p>¹⁴C analyses of groundwaters from the Chalk of the London Basin are re-interpreted and the age of the groundwater is revised. Radio-isotope analyses are used to examine the flow mechanism in the aquifer. The evidence supports the view that a network of micro-fissures and larger intergranular pores in the matrix provides a significant part of the water pumped from Chalk wells and the major fissures distribute the water to the wells. Most of the matrix is fine-grained and contains a very old water. This diffuses into the micro-fissures and larger pores and is carried to the wells by the major fissures.&nbsp;</p> application/pdf 10.1016/0022-1694(79)90088-X en Elsevier The flow mechanism in the Chalk based on radio-isotope analyses of groundwater in the London Basin article