Paleolightning is the study of lightning activity throughout Earth's history. Some studies have speculated that lightning activity played a crucial role in the development of not only Earth's early atmosphere, but also early life. Lightning, a non-biological process, has been found to produce biologically useful material through the oxidation and reduction of inorganic matter. Research on the impact of lightning on Earth's atmosphere continues today, especially with regard to feedback mechanisms of lightning-produced nitrate compounds on atmospheric composition and global average temperatures.
Detecting lightning activity in the geologic record can be difficult, given the instantaneous nature of lightning strikes in general. However, fulgurite, a glassy tube-like, crust-like, or irregular mineraloid that forms when lightning fuses soil, quartz sands, clay, rock, biomass, or caliche is prevalent in electrically-active regions around the globe and provides evidence of not only past lightning activity, but also patterns of convection. Since lightning channels carry an electric current to the ground, lightning can produce magnetic fields as well. While lightning-magnetic anomalies can provide evidence of lightning activity in a region, these anomalies are often problematic for those examining the magnetic record of rock types because they disguise the natural magnetic fields present.