What are metallic or silica-rich objects, 1m to 950 km in diameter, that bombarded early Earth, generating heat energy?

What are microscopic, photosynthetic prokaryotes that formed stromatolites and changed early Earth’s atmosphere by generating oxygen?

What is the change in species over time called?

What is the study of materials that make up Earth and the processes that form and change these materials, and the history of the planet and its life-forms since origin?

What is the period of time it takes for a radioactive isotope, such as carbon-14, to decay to one-half of its original amount?

Fill in the blank: A small fragment of an orbiting body that has fallen to Earth, generating heat, is called a _________.

Fill in the blank: The ancient geographic setting of an area is known as _________.

Fill in the blank: An informal unit of geologic time consisting of the first three eons during which Earth formed and became habitable is called the _________.

Fill in the blank: Emission of radioactive particles and its resulting change into other isotopes over time is known as _________

Fill in the blank: The process that determines the age of relatively young organic objects; objects that were alive or were once alive is called _________.