crap up vs silt

crap up is not a noun while silt is a noun.

Word	Noun	Adjective	Verb	Adverb
crap up	No	No	Yes	No
silt	Yes	No	Yes	No

As verbs, silt is a hyponym of crap up; that is, silt is a word with a more specific, narrower meaning than crap up:

Other hyponyms of crap up include gum up, block, choke up, lug, stuff, silt up.

crap up (noun)	silt (noun)
	mud or clay or small rocks deposited by a river or lake

crap up (verb)	silt (verb)
become or cause to become obstructed	become chocked with silt