I suggest that there is a check-box on each explorer/geologist, the same way it is when transferring generals to adventures.
So when you want to do for example marble search you can check/select each geologist that should do that search.
Or when you do for example medium treasure search, you can click/select each available explorer that should do that search, with 1 click.
So you don't have to send each explorer separately which is really annoying if you have like 10-12 explorers...(and you have to send each of them, 1-2 times per day ).