What is the age of the oldest rocks discovered on the planet?

Identify what happens to light in this model of the greenhouse effect

According to the earth science reference tables, during which geologic time period were the continents of north america,south america, and africa closest together?

Simple astronomical telescope the objective lens has a focal length of 75 cm and that of a piece of 5cm of the lenses are 18 cm apart when will be final image of a distant object before