Did mammoths and dinosaurs live at the same time?
Mammoths and dinosaurs did not live at the same time. Non-Avian dinosaurs went extinct on earth about 66 million years ago, and mammoths first appeared on earth about 1.8 million years ago, so there were about 64 million years between mammoths and dinosaurs existing.
Why are the continents older than the oceanic crust?
The continents are older than oceanic crust because the continents are not recycled through plate tectonics. Throughout the process of plate tectonics, the denser oceanic crust will be subducted underneath continental crust and melted into the mantle. For that reason, the lighter, more buoyant continental crust survives at convergent plate boundaries. Continental crust is more buoyant in these interactions because it is composed of felsic rock, which is less dense than basalt, which makes up the oceanic crust.
What is a rock and how is that different than a mineral?
A rock is an aggregate, or collection, of different minerals. Minerals are composed of homogeneous molecules of a particular type, arranged in a particular way.