What was Meriwether Lewis's job before the expedition?
He was Thomas Jefferson's personal secretary.
He was governor of Virginia.
He was .
He was a silversmith.

he was Thomas Jefferson's personal secretary.

Explanation:

Before the expedition, Lewis was Jefferson's private presidential secretary. He also served in the military, where he met Clark. After the expedition, Lewis served a short term as Governor of the Territory of Upper Louisiana before he died.

He was Thomas Jeffersons personal secretary.

radioactive dating, also known as  radioisotope dating  is a process that in  estimating the approximate  age  of  rocks. these data can be analyzed from  the studies dealing with the  decay of the radioactive elements that are present in these rocks. in nature, there are a few types of materials or atoms which are quite unstable and they spontaneously decay or breakdown to form other kinds of atoms.