Internal Structure of the Adjective Phrase

The adjectives of a noun phrase often have their own internal structure. This can result in ambiguity. In actual speech, stress and pauses can serve to disambiguate the phrase.

The noun phrase a dark blue hat contains the adjective phrase dark blue. The adjective dark can modify blue or hat. If the adjective modifies hat, the analysis is (dark) blue hat, and if the adjective modifies blue, the analysis is (dark blue) hat. 

We can also disambiguate by paraphrasing. In the analysis in which the word dark modifies blue, we can say that the hat is dark blue. In the second analysis, the one in which the word dark modifies hat, we can say that the hat is dark and blue.

Stress and pauses disambiguate phrases in actual speech. Speakers pause more between adjectives of equal status. This pause can be represented with a comma in writing. When dark modifies blue, dark is stressed more than blue. However, when dark modifies hat, both words are evenly stressed and there is a pause between dark and blue. 

Many adjective phrases precede nouns. In certain cases, their internal structure can lead to ambiguity. To make the meaning clear, it is possible to paraphrase. It is also possible to use stress and pauses to communicate the intended meaning.