Word-order with の- and に- particles

Question

I have this part of a sentence

影{かげ}の次第{しだい}に濃{こ}く集{あつ}まる部分{ぶぶん}に

along with its translation:

"in the part where the shadows gradually gathered and thickened"

which makes contextual sense, but still, I would have translated the sentence as "(where) the parts gradually thicken and gather inside the shadow(s)". So it is not the shadows that gather and deepen (contrary to the accompanying translation)

Where did I go wrong? Thanks a lot!

Answer 1

You could parse it this way..

［影の｛（次第に）濃く｝集まる］部分に

影の次第に濃く集まる is a relative clause modifying 部分, so you can rephrase it as 影が次第に濃く集まる部分に. 影 is the subject of 集まる. 次第に濃く adverbially modifies 集まる.