REVIEWS. 121 
the eastern portion of the anticlinal, inis east side of the minor ridges — gently down, 
vine the west side is abrupt; and on the western portion vice versa, But if we take the ridges 
singly and examine them, we shall tm ta most cases that the aggregate — p mearty ners 
west and south-east. The conseque 
mountain from rogers to south, tse cor ranges or ridges pre esent a sort of ** en echelon” ap- 
arance; that is, they run out one after the other in the prairies, preserving the nearly north 
and south ebura of the entire sisted Not unfrequently a group or several of these ridges 
will run out at the same time, e — a huge notch in the main range. This notch in most 
which give birth to a water system of greater or less extent. trem for example, is the noteh 
~ Cache a is Poudre, TORE ndo City, Canon City, on the Arkan as River, and other loca rest 
are beyond comparison the most correct and most scientific of our Rocks Mountain region in in 
existence, we s bvem uld at _— — the "nr: of ye es inet rang 
of fracture iti i iti 
north and en and "A these — pass out o or conse bod an end without prodome any 
3 14 
except perhaps. 
plain through the mo onoclinal rift. But when ‘several of apa minor ranges come to end to- 
e an abrupt jog of several miles towards the west is caused. Then d as rds range 
dies out, a "— anticlinal oF s €— cemedartiben (ied is ptm tothe sedimentary beds, Be- 
t th t of ridges or ** hog-backs” "riore es very 
narrow, sometimes hs hardly Maer m sometimes emey onno esten by superficial de- 
posits. But at these breaks the s ofr 
from half a mile to wae or fifteen m aie hi width, ft is in i these localities that the complete 
re s^ id country can be studied in detail. I do not Po of any portion of the 
uch d geolo; 
round "Colorado City. Neariy all the elements Edi geological cals revealed in t 
ie studying the mines of Colorado the explorer apres that ^g: lodes 
are almost invariably parallel, running north-east to south-w This 
and the two cleavage planes, one north-east to UR ide and ye other 
north-west to south-east, which he found to be peculiar to all the Azoic 
rocks, leads to an important and highly interesting generalization : 
“Tam inclined to neneve that the epist of the history of the — Mountain ranges is 
closely conne . As I have before stated, my own 
tamorpl 
‘pote h f 
mountains is north-west and south-east, and that the eruptive trend north-east and south- 
es l t 
d and sout ran, 
range with a metamorphic or granitic nucleus, the trend chan. around to north- 
pouth-nast. Many o of the ranges have a nucleus of metamorphic rocks Peal the cen = 
be composed of nt case the igneous ma- 
terial ds thrust - in eed be the same direction as the trend. It mes therefere pret 
h th eraptive: meer Ss we z pa veas subsequent to the elevation of the 
t in Soutl Colorado and New 
metamorphie : nucleus, 
P Jal] e H f E + 
P 
e them over large areas." 
GEOGRAPHICAL HANDBOOK OF ALL KNOWN Wee is the title e the 
eat and of the most praiseworthy of Fern-books, now so popular in 
and. This neat volume is by K. M. Lyell (Mrs. Cir. , Lyell), jä is 
just patioa by Murray; a small octavo of two hundred and twenty- 
pages. It gives in order, under the principal countries, a list of all 
inr Ferns, with range and localities, and then a full series of tables 
exhibiting the geographical distribution of each species through the sev- 
eral regions. 
AMER. NATURALIST, VOL. IV. 16 
