Question

From which of the Earth's layers do scientists collect samples?

Answer 1

The crust.

Explanation:

Humans can only sample the crust currently, the deepest samples from the crust have been 12,262 meters (40,230 ft) deep, those coming from the Kola Superdeep Borehole on the Kola peninsula of Russia.

Though a slight deviation, we also take samples from the ice caps, drilling big chunks out, which we carbon date, and measure the contents of the air trapped in them, which we can then use to see what the atmosphere of the world was like years ago.

Hope this helps and the extra info.