Abstract: A water and/or oil-impermeable sealing mat is provided in form of a bentonite non-woven fabric combination with the possibility of transmitting thrust from one batt layer to the other, i.e. on a slope thrust forces can be transmitted by the covering batt material through the layer of swellable clay into the supporting batt material. Such a sealing mat is a fiber-reinforced mineral seal permitting the transmission of thrust forces on slopes, without the risk of the layer of swellable clay itself becoming the preferred sliding plane. The sealing mat consists of a non-woven textile material as substrate layer, a layer of swellable clay, preferably sodium bentonite, and a cover layer consisting preferably also of a non-woven textile material, all three layers having been needled together in the conventional manner in a needle loom. When moistened, the clay swells and forms the water and/or oil-impermeable layer.