Distinguishing between 'on' and 'above'

Question

世界のルールで、島は水より上に出ていなければならないと決まっています。
World rules determine that an island must stick out above the water.

In this sentence 水より上 clearly means 'above the water', but when I look in bilingual dictionaries they just translate 'above' as 上. I wonder how this sentence would sound if より was omitted?

Supposing I had the sentence:

時計はテーブルの上にある。

Without further context would this be interpreted as "The clock is on the table" or "The clock is (on the wall) above the table"? Or is there ambiguity?

Would the ambiguity be removed if I wrote 時計はテーブルより上にある to mean above the table?

In summary, I'm just trying to understand the difference between の上に and より上に. Also, I wonder if より下 is used. There seems to be no need to distinguish between below and under.

Answer 1

世界のルールで、島は水より上に出ていなければならないと決まっています。
I wonder how this sentence would sound if より was omitted?

「世界のルールで、島は水の上に出ていなければならないと決まっています。」 would probably be okay but I think 水より上に～ is more natural and clear. 水より上に here means 水面/海面より上に or 水面/海面より高い位置に, "above / higher than the surface of the water/sea".

時計はテーブルの上にある。

It would usually be interpreted as "The clock is on the table", but it can also mean "The clock is (on the wall) above the table".

Would the ambiguity be removed if I wrote 時計はテーブルより上にある to mean above the table?

It wouldn't sound natural. I think this is because ～の上にある is talking about 位置関係 (positional relationship of two things/objects), while ～より上にある is talking about 比較してどちらが上にあるか (which is in a higher position).

In summary, I'm just trying to understand the difference between の上に and より上に. Also, I wonder if より下 is used. There seems to be no need to distinguish between below and under.

I think we use ～の上に to talk about the location of something, like one thing lies / is located on or above another, and ～より上に to say or emphasize one thing is in a higher position in comparison to another. And I think this also applies to ～の下に and ～より下に; I would say ～の下にある to mean "something lies / is located under/below something else", and ～より下にある, "something is in a lower position than something else".

Answer 2

Basically, the difference between "above", "on" and "over" is quite ambiguous in Japanese language.

時計はテーブルの上にある。

Without any context, this could be both "above the table" and "on the table". But it usually means "on the table" without any context.

より上 doesn't mean "on", so if you want to make it clear, you can use より上.

But most of the time it sounds strange if you use より上 to say 'above'. For instance

Seagulls are flying above the sea.

is カモメは海の上を飛んでいる, should not be カモメは海より上を飛んでいる. This is not grammatically "wrong" but it sounds strange because it is obvious that this 上 means "above". You should use より上 when this is not obvious.

And より下 is same as above.