1
general::
Also, dwell upon. Linger over; ponder, speak or write at length. For example, Let's not dwell on this topic too long; we have a lot to cover today. [c. 1500]
American Heritage Idioms
2
general::
Phrase(s): dwell (up)on someone or something
to remain on the [important] subject of someone or something for a long time. (Upon is formal and less commonly used than on.) • I can’t dwell upon this subject anymore. • There is no need to dwell on Sarah further., Phrase(s): dwell (up)on something
to live on something, such as the planet Earth. (Upon is more formal than on.) • This is the largest turtle that dwells upon the earth. • Many creatures dwell on this earth.
McGrawhill's American Idioms And Phrasal Verbs