Simplify the following text for a Grade 10 native English-speaking person.
Original: The first mineral discoveries in the Top End were associated with the construction of the Overland Telegraph line between 1870 and 1872 , in the Pine Creek â `` Adelaide River area .
Simplified: Minerals were found in the Top End during the building of the Overland Telegraph line between 1870 and 1872 , in the Pine Creek â `` Adelaide River area .