Don’t end a sentence with a preposition
۱ In formal writing
It’s not an error to end a sentence with a preposition, but it is a little less formal. In emails, text messages, and notes to friends, it’s perfectly fine. But if you’re writing a research paper or submitting a business proposal and you want to sound very formal, avoid ending sentences with prepositions.
۲ If something is missing
The preposition atop is missing an object all together. Let’s try that again:
It’s ok to end a sentence with a preposition
۱ In informal writing or conversation
Unless you’re a time traveler from another era, you’ll probably use the second sentence when speaking. Informal language is generally accepted in conversation and will likely allow your conversation to flow more smoothly since your friends won’t be distracted by your perfectly precise sentence construction.
۲ If the preposition is part of an informal phrase
Both ‘put up with’ and ‘hard to come by’ are commonly accepted informal phrases, and it’s OK to end sentences with them. Note, however, that you should avoid these phrases in formal writing.