Tidal bundle decreases as the tidal variation grows smaller, towards the neap tide again and the thinnest beds. The presence of tidal bundles depends on the presence of spring and neap tides, which can only occur in three-body gravitational systems (the Earth, the Sun and the Moon). Therefore, the earliest time from which tidal bundles can be identified gives a conclusive lower bound on the age of the Moon. Tidal bundle A tidal bundle is a sedimentary structure that forms in tidal areas as a result of spring and neap tides. A tidal bundle sequence can be seen as a variation in
Issues relating to biofuels ecosystems including rainforest in South America. In forest ecosystems, these effects themselves will undermine the climate benefits of alternative fuels, in addition to representing a major threat to global biodiversity. Although biofuels are generally considered to improve net carbon output, biodiesel and other fuels do produce local air pollution, including nitrogen oxides, the principal cause of smog. Issues relating to biofuels There are various social, economic, environmental and technical issues with biofuel production and use, which have been discussed in the popular media and scientific journals. These include: the effect of moderating oil prices, the "food vs fuel" debate, poverty