を vs で in these sentences


Can't understand Kanji, so please use furigana in answers :)

Context: I'm using Rosetta stone, so there's just pictures. The picture
accompanying the first sentence is a girl sleeping on a beach, the picture for
the second sentence is just some random guy in mid-stride, walking on top of a
mountain.

> おんなのこは かいがんで ねています
>
> おとこのひとは やまを あるいています

I'm confused about the use of で in one and the use of を in the other. As I
understand it, で implies wandering around inside some fixed borders, whereas を
indicates going through a location.

Would I be right in thinking the first sentence uses で to imply the girl is
sleeping on the beach/within the borders of the beach, and を implies the man
is walking _through_ the mountains, not within them?




~を together with an motional intransitive verb means "through ~" as you
correctly figured out.

~に before an motional verb defines the destination of the movement.

These two uses can't be applied on 寝{ね}る (*) though, because sleeping
obviously doesn't contain any motion. I prefer to think of the ~で particle as
a "context marker". In which context are you sleeping? In the locational
context of the beach. Or another example: かぜで [学校]{がっこう}を[休]{やす}んだ。 In the
context of/because of a cold, I didn't go to school.

(*) As snailboat pointed out, 寝る does not only have the meaning "to sleep",
but "to lie down" as well. Of course this is a motion and can be put together
with ~に, for example: かいがんに寝る means "to lie down on the beach".




~を together with an motional intransitive verb means "through ~" as you
correctly figured out.

~に before an motional verb defines the destination of the movement.

These two uses can't be applied on 寝{ね}る (*) though, because sleeping
obviously doesn't contain any motion. I prefer to think of the ~で particle as
a "context marker". In which context are you sleeping? In the locational
context of the beach. Or another example: かぜで [学校]{がっこう}を[休]{やす}んだ。 In the
context of/because of a cold, I didn't go to school.

(*) As snailboat pointed out, 寝る does not only have the meaning "to sleep",
but "to lie down" as well. Of course this is a motion and can be put together
with ~に, for example: かいがんに寝る means "to lie down on the beach".

