In recent years, citizen oriented applications have been developed with Geographic Information Systems (GIS). This is the reason why visual querying appears to be crucial. Many approaches for visual querying or browsing spatio-temporal data have been proposed recently. Geographic databases represent a spatio-temporal continuum. This is the reason why visual languages must integrate temporal data handling. We develop a visual language based on a query-by-example philosophy for spatial and temporal data. A query is formulated by means of predefined icons which map spatial and temporal objects and operators. New visual metaphors such as balloons and anchors are proposed in order to express spatial and temporal criteria. After a state of the art of visual querying for geographic databases, we define a spatio-temporal model. The visual language and its user interface are then explained. Samples are proposed upon a road risk management application. In this sample database both discrete and continuous temporal data are taken into account: moving points such as trucks, and lifecycle objects such as rivers. We then conclude about our future work.