To explain the distributions of LIPs in time and place, volcanologists refer to plates, hotspots and/or mantle plumes, much of which which are far from our direct access. These plates, hotspots and plumes come and go, plates move over hotspots and/or plumes, and time/space series patterns are not clearly defined or forecastable. This requires volcanologists to consider the deep thermal origin of volcanism, which is fundamental geophysics of the deep earth and especially the mantle and core. For obscure causes, deep earth heat transfer leads to massive volcanism at rare intervals and in widely scattered surficial locations.  The surface manifestations may be huge volumes of volcanic rocks. The environmental consequences must be large, but are mostly uncertain. From the recent record of LIPs, a relationship of the timing of LIPs with extinctions of living species is advanced.