Meskó Csaba: Thermal Baths - Our Budapest (Budapest, 1999)
sures between these two rock formations of very different ages forms an enormous reservoir of karst water. Marlite layers of significant depths and breadths also belong to these early Tertiary formations. The major component of marl is clay and it also contains a significant proportion of lime. Due to tectonic shifts, these are cracked-up, fragmented layers, whose fissures and passages were widened out through the dissolving of rock containing water as with chalk and dolomite. It was over the next, Oligocene, part of the early Tertiary period that successive layers of grey clay sedimented from the sea covering the region at the time. Although layers of sand and sandstone between those of clay conduct water, as the former is rather thin the water contained in them is of no significant quantity. Karst water held in the fissures, passages and recesses of the cavernous rock can be cold, lukewarm or hot. The table of subsoil water rests upon the first layer of impermeable rock, usually filling intervening spaces in granulöse rock. The conductive layer between two layers of impermeable rock contains interstratal water in the spaces between its granules. Waters stored in the various layers of water-storing rock usually remain separate. Water trapped in formations resting upon one another or intersecting along structural planes can, however, mix, depending on the extent to which their layers are interconnected. The blending of various types of water can occur where the storing rocks approximate or reach the surface or come into contiguity with each other in the deep. It is where hill meets basin that several fissures separating parts of very different structural makeup occur, and various layers come into contact even in the form of direct overlap. This is represented by the line of the Danube, especially on the Buda side. THE THERMAL AMD MEDICINAL WATERS OF THE CAPITAL Hungary’s thermal waters originate in precipitation. Precipitation seeping in re-emerges in the form of thermal and medicinal water hundreds or thousands of years later. The thermal waters of Budapest fall into categories according to location, water-yielding layer, quantity of dissolved minerals and temperature. Hydro-engineer Eva Balogh de16
