frigid z o n e , a r e th e re s u lts o f a c lim a te w h ic h a p p e a r s f a v o u ra b le to th e
p a s sa g e o f tro p ic a l fo rm s b e y o n d th e i r p ro p e r lim its , a n d to a v ig o ro u s
n a tiv e v e g e ta tio n . T h e c lim a te is o n e o f a n e q u a b le n a tu r e ; a n d th is
m u s t, to a c o n s id e r a b le d eg re e , b e th e effe c t o f th e g r e a t a r e a o f o c e an
c om p a r e d w ith th e la n d o f t h e s o u th e rn h em is p h e re . I n th e n o r th e rn h e m
is p h e re we h a v e p ro o fs , t h a t th e p ro d u c tio n s b o th o f t h e la n d a n d w a te r,
d u r in g th e p e rio d a n te c e d e n t to th e p r e s e n t, h a d a m o re tro p ic a l c h a ra c t
e r th a n th e y n ow h a v e , a n d th e r e is, a lso , a h ig h d e g re e o f p ro b a b ility t h a t
th e p ro p o r tio n a l a r e a o f w a te r was m u c h g r e a te r.
I f th e n w e ju d g e from th e a n a lo g y o f th e s o u th e rn h em is p h e re , th e
firs t a n d s im p le in fe r e n c e from th e s e facts, is, t h a t t h e t em p e r a tu r e o f E u ro p e
w a s fo rm e rly m o re e q u a b le , th o u g h p e rh a p s w ith a low e r m e a n , th a n i t
n ow is. I t m ay b e a sk e d , a s a t e s t o f th is in fe ren c e , d id th e sn ow -h n e
fo rm e rly d e sc e n d low e r th a n i t n ow d o e s ? W a s th e so il fo rm e rly fro z e n
a l i t t l e b e n e a th th e su rfa c e in a low l a t i tu d e ? T h e c o n g e ale d carcasses
o f t h e g r e a t P a c h y d e rm a ta o f S ib e ria a n sw e r th e s e co n d q u e s tio n ; a n d in
m y jo u rn a l , I h a v e in d ir e c tly c o n s id e re d th e firs t o n e as a n sw e red , b y th e
fa c t o f th e m an y e r r a tic b o u ld e r s o f E u ro p e h a v in g tra v e lle d from m o u n ta
in s , s itu a te d in reg io n s w h e r e g r e a t b o d ie s o f ice d o n o t a t p r e s e n t d e s cen d
to th e lev e l o f t h e se a. F o r o n th e th e o ry t h a t th e s e b o u ld e r s w e re tra n s p
o r te d b y iceb e rg s from g lac ie rs , w h ic h fo rm e rly d e s c e n d e d in to th e se a in
l a t i tu d e s w h e r e p e rp e tu a l sn ow is n o t n ow fo u n d , o r i f so, o n ly a t g r e a t
h e ig h ts , th e p ro b lem rec e iv es so s im p le a s o lu tio n , t h a t I d id n o t h e s ita te ,
h a v in g th e o th e r d a ta , to a s sum e , t h a t th e sn ow -lin e in E u r o p e fo rm e rly
d id d e sc e n d m u c h low e r th a n i t d o e s a t p r e s e n t. B u t, h a d I s tu d ie d m y
s u b je c t m o re a tte n tiv e ly , I m ig h t h a v e ta k e n a h ig h e r g ro u n d ; in a n o te ,
in d e e d ( p . 2 9 4 ), I h a v e s ta t e d t h a t a c c o rd in g to P ro fe s s o r E sm a rk , i t is
c e r ta in , t h a t th e g la c ie rs o f N o rw a y fo rm e rly d e s c e n d e d to a low e r lev e l ;
a n d I n ow fo u n d t h a t som e tim e sin c e , M e ss rs . V e n e tz a n d C h a rp e n tie r ,
a n d m o re la te ly M. Ag assiz, h a v e in c o n te s ta b ly sh ow n , from th e p re s e n c e
o f g la c ie r-d ik e s o r m o ra in e s , a n d from th e p o lish e d a n d s c ra tc h e d su rfa c e
o f t h e ro ck s, t h a t in th e A lp s e n o rm o u s b o d ie s o f ice fo rm e rly d e s c e n d e d
to th e b o rd e rs e v e n o f th e la k e o f G e n e v a , a n d th e r e fo r e m u ch low e r th a n
th e lin e o f p r e s e n t low e s t d e s c e n t.* W ith th e s e se v era l facts i t m ig h t
h a v e b e e n b o ld ly a s s e r te d , t h a t th e c lim a te o f E u ro p e fo rm e rly was lik e
* N o d o u b t i f m u c h m o re sn ow fe ll fo rm e rly th a n a t p r e s e n t, th e
g lac ie rs w o u ld fo rm e rly h a v e d e s c e n d e d s om ew h a t low e r ; b u t as E u ro p e
n ow h a s a m o d e r a te ly h um id c lim a te , i t is im p ro b a b le in th e h ig h e s t
d e g re e ( i f in d e e d p o s s ib le ) t h a t a d iffe re n c e o f t h a t k in d c o u ld h av e
c a u se d th e fo rm e r e x tr em e ly low d e s c e n t o f th e a n c ie n t glaciei-s o f th e
A lp s : th e r e fo r e w e a r e c om p e lle d to a tt r ib u t e th e d iffe re n c e to a ch a n g e
o f t em p e r a tu r e o f som e k in d .
t h a t o f th e s o u th e rn h em is p h e re as i t n ow i s ; a n d c o n s e q u e n tly , as we
k n ow , t b a t th e se a w ith in r e c e n t te r t ia r y p e rio d s s to o d a t a h ig h e r le v e l
o v e r a la rg e p o r tio n o f o u r c o n tin e n t, i t m ig h t h a v e b e e n affirm ed , h a d
tlie re b e e n n o r e c o rd o f th e e x is te n c e o f e r r a tic b lo ck s o n th is s id e o f th e
g lo b e , t h a t i t w o u ld b e a n a n om a ly , d iffic u lt o f e x p la n a tio n , sh o u ld th e r e
n o t b e fo u n d a ro u n d th e em in e n c e s o f c e n tr a l a n d n o r th e r n E u r o p e g r e a t
u n ro lle d fra gm en ts , s c a tte r e d a t lo n g d is ta n c e s from th e i r p a r e n t so u rc e s ,
a n d o fte n s e p a r a te d from th em b y p ro fo u n d va lley s.
M . Ag a ssiz h a s la te ly {Address to the Helvetic Society, Ju ly 1 837,
translated in Jameson’s N ew Philosophical J o u r n a l,y d . x x iiL , p . 3G4, and in
several communications in the French periodical L ’In stitu t) w r itte n o n th e
s u b je c t o f th e g lac ie rs a n d b o u ld e r s o f th e A lp s . H e c le a r ly p ro v e s , as
I t a p p e a r s to m e, t h a t th e p re s e n c e o f th e b o u ld e r s o n th e J u r a c a n n o t b e
e x p la in e d b y a n y d e b a cle , o r b y th e p ow e r o f a n c ie n t g lac ie rs d r iv in g
b e fo r e th em m o ra in e s , o r b y th e s u b s e q u e n t e le v a tio n o f th e su rfa c e on
wh ich th e b o u ld e r s n ow lie . M . Ag a ssiz a lso d e n ie s tb a t th e y w e re
t r a n s p o r te d b y flo a tin g ice, b u t h e d o e s n o t fu lly s ta t e h is o b je c tio n s to th is
th e o r y ; n o r does h e o p p o s e it, b y th e a rg um e n t o f th e a p p a r e n t a n om a ly o f
a low d e s c e n t o f g lac ie rs, w ith th e g e n e ra lly -re c e iv e d o p in io n o f th e m o re
tro p ic a l c h a ra c te r o f th e p ro d u c tio n s o f th e a n te c e d e n t p e rio d s ,— w h ic h was
p h ilo so p h ic a l, u n t il th e e ffe c ts o f a tem p e r a te a n d e q u a b le c lim a te w e re
co n s id e re d .* O n th e c o n tr a ry , h e a s sum e s th a t , d u r in g th e g r a d u a l c o o lin g
o f th e e a rth , th e r e h a v e b e e n p e rio d s o f ex cessiv e re f r ig e r a tio n . I t is
n e e d le s s to s ta t e th a t su c h a n h y p o th e s is is n o t s u p p o r te d b y a s in g le
fa c t— w ith o u t, in d e e d , th e assumed su d d e n re n ew a l o f life o n th e su rfa c e o f
th e w o rld a t su ccessiv e p e rio d s b e c o n s id e r e d s u c h . D u r in g th is im a g in ed
p e rio d o f e x c essiv e r e f r ig e r a tio n , th e A lp s a n d th e g r e a te r p a r t o f E u ro p e ,
a n d even o f A s ia , a re su p p o s e d to h a v e b e e n c o v e re d b y o n e im m e n se
s h e e t o f ice, a n d d u r in g th e assumed s u d d e n e le v a tio n o f t h e A lp s , fra g m
e n ts o f ro ck s a r e s u p p o s e d to h a v e b e e n s h o t o v e r th e fro zen su rfa c e ,
a n d , w h e n th e ice m e lte d , to h a v e d ro p p e d o n th e su rfa c e w h e r e th e y n ow
lie . M . Ag a ssiz co n s id e rs t h a t th is v iew e x p la in s th e p o s itio n o f th e
b o u ld e r s o n p in n a c le s , a n d th e i r a b s e n c e in th e v a lle y s . I co n fess I
sh o u ld h a v e th o u g h t, a f te r th e , f le x u re a n d e le v a tio n o f th e ice , th e s e
w o u ld h a v e b e e n th e le a s t p ro b a b le s i tu a t io n s : b u t n e ith e r th is , o r som e
* M . C h a rp e n tie r {in his account o f M . Venetz’s investigaiio?is on the
Glaciers o f the Falais— Edinburgh Netu Philosophical Journal, v o l. x x i., p .
2 1 5 ) w a s fu lly aw a r e o f th is d ifficu lty . H is e x p la n a tio n re s ts o n a s u p p
o s e d e n o rm o u s o s c illa tio n o f lev e l in th e A lp s ,—a n a s sum p tio n w h ic h is
u n s u p p o r te d b y o th e r fac ts , a n d is n o t a p p lic a b le to th e g e n e ra l c a se o f
E u r o p e .