Korean Job Discussion Forums

[Faunaki]

I can't answer my K teacher's grammar question, please help me.

From this sentence:

Active volcanoes can also produce pyroclastic flows, which are fast moving rivers of fluidized hot gas, ash and rock, or lahars, which are mixtures of rock, mud, and water with the consistency of concrete that usually flow from the volcano down river valleys at high speeds.

So the problem is "that" which refers to lahars.

The question is why can lahars be modified twice - first by which and then by that? She feels that "that" should modify concrete and not lahars. In this situation a noun is modified twice, but what is the grammar rule for that?

TKS

[sirfro]

"That" wouldn't modify concrete. Lahars are being described as having the 'consistency of concrete'... no?

[some waygug-in]

My guess it that "that" in the passage you cited modifies "mixtures" and not
Lahars.


I'm no grammarian though.

[A2Steve]

Or just tell her it's a run-on sentence that is too long and would better for a layperson if it was split into two or more sentences.


sometimes the easiest explanations are the best.

[Faunaki]

[Underwaterbob]

I would suggest there should be a comma after "concrete" in order for the "that" to more clearly modify "lahars". The whole of "which are mixtures of rock, mud, and water with the consistency of concrete" is more or less a descriptive aside.

I have no knowledge of rules regarding modifying nouns twice.

Like A2Steve mentioned, it's way too long. It could be re-written into two or three sentences and be much easier to understand.

[Jennie]

The book's wrong, some waygug's right. It definitely modifies mixture.

It's more obvious if you take out the three prepositional phrases:

...which are mixtures (of rock, mud, and water with the consistency of concrete) that usually flow from the volcano down river valleys at high speeds...

[jkelly80]

Seconded. The prep. phrases are adjuncts, not necessary to the syntax of the sentence. Waeg is right, book is wrong.

[Unposter]

I personally think Underwaterbob has got it right.

[The Cosmic Hum]

Active volcanoes can also produce pyroclastic flows, which are fast moving rivers of fluidized hot gas, ash and rock, or lahars, which are mixtures of rock, mud, and water with the consistency of concrete that usually flow from the volcano down river valleys at high speeds.

It would appear that this sentence is trying to demonstrate the usage of the relative clause.
(, which are fast moving rivers)�nonrestrictive relative clause�indicated by comma
(, which are mixtures)�nonrestrictive relative clause�indicated by comma
(that usually flow)�restrictive relative clause�.no comma required in this case ( when using that�that indicates a restrictive relative clause�so no comma is being used�this is the cause of confusion as it could easily be assumed that �that� was intended to modify concrete.)

As to why lahars is being modified twice�.one is a description of what lahars are�.the second is a description of what lahars do.
Your teacher makes a good point in thinking �that� modifies concrete�but under closer inspection it becomes clearer that �that� is modifying lahars�though poorly and deceptively worded.

However, it could clearly be argued that�that usually flow�is modifying pyroclastic flows.
Only the author of this abomination of clauses could rightly say what is being modified here.

[Lekker]

fluidized

[Faunaki]