255(Poutsma 1917: 971; Curme 1935 : 46; Quirk et al. 1985 : 1112). According
to Jespersen , what’s more is “a special kind of clause, in which the speaker
(writer) interrupts the fl ow of the sentence to give as it were his own com-
ment on some idea or expression”; psychologically it functions as a “mental
parenthes[is]” (Jespersen 1927 [1961]: 113). More specifi cally, what’s more
is seen as expressing expansion, addition, or elaboration, what Keller ( 1979 :
224) calls a “subject- expansion,” Quirk et al. ( 1985 : 663) call “listing- additive-
reinforcing,” and Fraser ( 1999 : 948) calls “elaborative.” Elaborative discourse
markers as those that “indicate a relationship in which the message of S2 paral-
lels and possibly augments or refi nes the message of S1” (Fraser 1999 : 948). In
more everyday terms, the Cambridge advanced learner’s dictionary (s.v. what )
describes what’s more as being “used to add something surprising or interest-
ing to what you have just said.”
As an additive marker, what’s more is often equated with conjunct adverbi-
als, such as above all , also , furthermore , in particular , moreover , on top of
it all , to cap it (all) (off) , too (see Quirk et al. 1985 : 635; Fraser 1999 : 948;
OED: s.v. what ). What’s more (and its variants) is the only fi nite clausal con-
junct (Quirk et al. 1985 : 1069).^4
9.2.2 Synchronic Parallels
Grammars point to a parallel between what is more Adj clauses (as in 5a)
and sentential relative which - clauses, which is more Adj (as in 5b) (Poutsma
1917: 971; Quirk et al. 1985 : 1117, 1120). And indeed, we can fi nd occasional
examples of such which- clauses in Present- day English corpora (5c– d), though
they also function as regular non- restrictive relative clauses (5e).
(5) a. What’s more surprising , he didn’t inform his parents.
b. He didn’t inform his parents, which is more surprising.
c. If heavier and somewhat complex, which is more probable , the containers
might be restricted to garages or car dealers with knowledgeable staff. (2000
Environment [COCA])
d. I believe also, later on this year, in September, which is more worrying , you
have the Cassini space shot carrying 76 pounds of plutonium, (NPR Science
[COCA])
e. foreign observers who concentrated on measuring gamma radiation, which is
more severe , but shorter- lived. (1990 Christian Science Monitor [COCA])
f. Which is more dangerous , a blood transfusion or an organ transplant, in
terms of getting AIDS? (1991 ABC Nightline [COCA])
g. Which is more important , plenty of living space or light weight? (2001
Backpacker [COCA])
4 Fraser ( 1999 : 948) adds the additional clausal conjuncts that is (to say) (see Brinton
2008 : 104– 109).
9.2 What’s More in Present-Day English