Understanding 一面の緑 in this sentence


> 窓をがらりと開ければそこは一面の緑。

I'm not sure what the end of the sentence means. I can guess that when he
opened the window, there was some vegetation but I don't understand how the
last part (一面の緑) works. What exactly does that mean and why does it make
sense?




It means a 'Sea/Blanket of green(ery)'.

According to 大辞林, one of the definitions of 一面 is: ある場所全体。そのあたりいったい。Hence, the
whole area, or possibly colloquially paraphrased in a literary fashion as
applies to the example in the question 'as far as the eye can see'.

An [ALC search](https://eow.alc.co.jp/search?q=%E4%B8%80%E9%9D%A2%E3%81%AE)
shows that this expression applies to vertical and horizontal planes alike,
whether it be a 'blanket of snow' or a 'wall of ivy'.

In this case, using [punipunijapan's
explanation](http://www.punipunijapan.com/grammar-lesson-3-particle-%E3%81%AE-
no/) of の might be helpful. Thinking of this usage of の as 'of', rather than a
strict possessive sense should hopefully help this construction seem more
natural (日本語の本、英語の先生）. 緑 in this case refers to greenery (a noun), not the
color green (can be adjectival). Substituting another noun like 森 or 雪 might
make this pattern more understandable.  
名詞+の is saying something specific (describing something) **about** the
following noun, hence it is acting in an adverbial fashion. If it were 緑の一面 it
would be describing the area as green, rather than describing the green as
'everywhere'.




It means a 'Sea/Blanket of green(ery)'.

According to 大辞林, one of the definitions of 一面 is: ある場所全体。そのあたりいったい。Hence, the
whole area, or possibly colloquially paraphrased in a literary fashion as
applies to the example in the question 'as far as the eye can see'.

An [ALC search](https://eow.alc.co.jp/search?q=%E4%B8%80%E9%9D%A2%E3%81%AE)
shows that this expression applies to vertical and horizontal planes alike,
whether it be a 'blanket of snow' or a 'wall of ivy'.

In this case, using [punipunijapan's
explanation](http://www.punipunijapan.com/grammar-lesson-3-particle-%E3%81%AE-
no/) of の might be helpful. Thinking of this usage of の as 'of', rather than a
strict possessive sense should hopefully help this construction seem more
natural (日本語の本、英語の先生）. 緑 in this case refers to greenery (a noun), not the
color green (can be adjectival). Substituting another noun like 森 or 雪 might
make this pattern more understandable.  
名詞+の is saying something specific (describing something) **about** the
following noun, hence it is acting in an adverbial fashion. If it were 緑の一面 it
would be describing the area as green, rather than describing the green as
'everywhere'.

