Evolution of Earth and Life

Evolution of Earth's Continents and Crust Formation

• The lecture discusses the development and growth of continents
• Questions raised include how continents are formed from the same mantle that creates mafic rock, how continents grow, and which came first - the atmosphere or the continents
• The geologic time scale is mentioned, with specific time periods such as 66 million years, 251 million years, 542 million years, 2500 million years, and 4000 million years being highlighted
• The formation of the Earth's crust is discussed, with the possibility of crust formation even in the Hadean period and the importance of investigating Hadean detrital zircons for understanding continental crust development
• It is suggested that crust development may have occurred at lower temperatures, potentially leading to the formation of granitic crust
• The development of olivine-rich rocks called peridotite is mentioned, which settle down due to their weight and contribute to the formation of the mantle
• Rocks with pyroxene and plagioclase feldspar, known as basalt, are produced from peridotite, and their lower density allows them to "float," leading to the creation of oceanic crust
• Oceanic crust is responsible for the creation of lowlands, which later filled up with water to form the oceans
• The formation of granitic crust is also discussed, but further details are not provided in the given text