872 Murchison’s Siluria. 
much we lose in the rapidity and accuracy of our observations 
for want of good geographical maps. European geologists have 
as a basis for their operations almost an exact miniature copy of 
the surface, on which every elevation, every undulation of the 
ground, every land-mark, every stream and almost every house 
is laid down. With such maps he is not obliged to be his own 
surveyor, topographer and draughtsman, and he is never at a loss 
e he is in the world. Another great advantage 
which an old and thickly inhabited country possesses over a new 
one, is the aid afforded by artificial sections of the rocks, such as 
are furnished by canal and railway cuttings, deep wells, mines or 
quarries. When the structure of a country is complicated, such 
helps become of the greatest fmportance, and the geologist who 
is deprived of their aid is often obliged to leave the most inter- 
esting problems unsolved. Great Britain, small as is the, space 
she occupies on the map of the world, is the first of nations in 
mineral and metallic wealth, and depends more exclusively for 
her national prosperity on that branch of her industry @vith which 
is most intimately connected, than any other country. 
Thus it is that this science has at all times been a favorite there, 
and its cultivators have been numerous, devoted and highly suc- 
cessful. 
In the course of the development of English geology those 
rocks naturally got the first attention which were most accessible, 
most thickly filled with organic remains, and most simple in their 
stratigraphical position. 'The remoter districts of Wales and the 
north of England were comparatively neglected, under the idea 
that the rocks of those regions were too scantily supplied with 
ssils and too much metamorphosed ever to be reduced to a sys- 
tem of ‘consecutive groups. The same was the case on the con- 
tinent. The German geologists-had contented themselves with 
calling all the rocks below the Old Red Sandstone primary and_ 
transition; but the line of division between them was rarely at- 
tempted to be drawn. Grauiwacke was one of those indefinite 
names under which were ranged a great variety of rocks of differ- 
ent ages. Some attempts were made, it is true, to separate t 
transition rocks in Germany into groups; but as these classifica- 
tions were based on mineralogical and not on paleontological 
grounds, they were of no value in any general application ; they 
implied no real progress in the task of unravelling the order 0 
succession of the older rocks. he first step in the right direc- 
tion seems to have been taken by Hisinger, who showed, in 1826, 
that the older fossiliferous rocks of Sweden might be separated 
into two groups, according to the nature of their fossil contents. 
In this country we were quite as completely in the dirk on 
the subject of our geological formations as they were 
in Europe in regard to their own. In the words of Murch 
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