Xとした usage and grammar?

Question

I've looked over my books but I can't find the answer. All I know is that とする can be used to express something you assume. Such as 温度は一定とする。 We assume the temperate is constant. Also I read we can use it for feelings such as ほっとする and look. So where can I read about this other usage? I have an example meaning too.

Can anyone please be so kind and explain how this grammar works as used down below.

周囲は暗く鬱蒼{うっそう}とした林に覆われていて、周りには街灯も少ないから夜なんて真っ暗だ。

Answer 1

Let me break your 鬱蒼とした into the parts of the speech.

鬱蒼とした is separated into 鬱蒼　( to Japanese language learners this is frequently called as na-adjective, but I would like to call it as quasi-adjective ( adjective noun ), and here, it is used as the stem of the quasi-adjective = A noun that functions as an adjective. ( Kindly be reminded there are many disputes regarding how to deal with this as the na-adjective or if it is the noun+auxiliary etc.　( For example, Motoki Tokieda is taking the latter stance. Here I would like to the latter stance. ) meaning, profuse, dense, thick etc, ) / と, case-marking particle, followed by the substantive, ( please see grammar ), meaning like, as if, etc ( Please refer to the further information below ) / し ( 連用形（れんようけい）,the continuative form ( meaning, to be continued to such as verbs, auxiliaries etc.. ) of the verb する, meaning, do or be ( this case ) /　た, 連体形,the attributive form ( meaning, after this follows a noun, so in your sentence the noun 林, forest ) of the auxiliary た, which denotes here the continuation. )

So if you take not 鬱蒼とした, but 鬱蒼とした林, after the long and complicated Japanese grammar above, it would stand as a subjective, meaning "dense, thick, dark, etc, forest".

Now let's take a look at the case marking particle

From the source, 4,

山と積まれた乾草

meaning, 乾草, a noun, meaning dried grasses or hay,

The translation will be

the accumulated hay like a mountain.

Doesn't it sound similar?

Hope I could somehow help.

Have a happy day.