This research aims to better understand drainage systems during mid to late Large Igneous Province (LIP) formation. A multidisciplinary study was conducted on the Lewiston Basin in the Columbia River Flood Basalt Province and the Skye Lava Field in the North Atlantic Igneous Province. A general model for drainage systems in LIPs was developed with three stages. In the early-LIP stage, the volcanic and drainage systems are confined to small basins, but as the volumetric eruption rate increases the regional drainage system is forced to the edge of the lava field. During the mid-LIP stage, the eruption rate decreases and the drainage system moves into the lava field, depositing channel sediments in the lowest parts of province while finer sediments or palaeosols develop in topographically higher areas. In the Skye Lava Field the drainage system was dominated by the uplift of the Rum Central Igneous Complex and included the incision of shallow valleys, whereas in the Lewiston Basin the most important effect was the structural control on basin topography. During the lateLIP stage, topographically high areas experience significant incision into the lava field which are filled by intracanyon flows (thick canyon-filling lava flows). These intracanyon flows may compartmentalise potential reservoirs deposited between earlier lava flows. Siliciclastic sand bodies were observed up to 12 m thick and 850 m across with minor exposure gaps, and were correlated across up to 15 km. The palynofloras associated with a number of palaeoenvironments in each province were identified the effects of other controls on the palaeoecology such as moisture availability, ashfall and substrate were established. The changes in the paJaeoclimate of the Lewiston Basin were studied using palaeosol geochemistry and palynology.