I was wondering if someone could explain the difference between "encroach on/upon" and "encroach into". I cannot figure out the clear difference between them. Here are two sample sentences.
Each year the sea continues to encroach upon the island's beaches.
The suburbs encroach further into the rural areas each year.
In the first case, you have a moving target. The beaches are receding as the sea advances. The sea can't encroach into the beach because then it's not a beach anymore. Encroaching on tends to go with the idea of one thing displacing something else.
In the second case, you have a fixed target - some rural area. The 'burbs are encroaching into this area. They are changing the character of this formerly rural place.
It's basically an idiomatic preference, but there is some logic to it in most cases.
"Into" is rarely seen in this context, but the two meanings should be relatively obvious.
The sea, as it rises, crawls higher and higher over the adjacent shores.
On the other hand, the suburbs, as they grow, spread their tentacles out into the surrounding rural areas.
