I just looked up the word 'avalanche' in Longman Contemporary and it gives this definition:

a large mass of snow, ice, and rocks that falls down the side of a mountain

Why does does the verb that follows 'that' ends with an 's' ? Here, 'falls'.

Shouldn't 'fall' agree with what is preceded before 'that' i.e. 'snow, ice, rocks'. Becasuse 'rocks' is plural, isn't it? Grammar, I think, says the verb after a relative pronoun must agree with the nouns before the relative prounoun.


2 Answers 2


If the box of chocolate pieces sits in the sun, its contents will melt.

of chocolate pieces modifies box.

Singular box is the subject of the verb sits.

If the mass of rocks is dislodged, it will crash down the mountainside.

You could probably say "they will crash down" without a problem, because antecedents of pronouns have more freedom to be semantic; but "are dislodged" would be much closer to being ungrammatical.

  • Yea, thank you guys 😊. That was a rookie learner's mistake 😉
    – Yuri
    Mar 3, 2016 at 11:51

The agreement here is with "mass" not with "snow, ice and rocks". Since mass is the subject.

edit: I wonder what really would happen if you did have "fall". I think then the agreement would be with "snow, ice and rocks" thus changing the sentence structure and making all of "of snow, ice, and rocks that fall down the side of a mountain" one adjective phrase? I think that works fine though it seems strange?

  • Is mass a group noun like team, band, or group?
    – Yuri
    Mar 3, 2016 at 11:44

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