6 
EXPLANATION OF PLATE 1. 
if they had been injected, either at the time of, or after the 
elevation of all the strata, and had produced but little 
disturbance in the rocks through which they are protruded. 
It should however be understood, distinctly, that some In- 
jections may have preceded the elevation of Strata to their 
present height, and that numerous and successive eleva- 
tions and injections, attended by various degrees of frac- 
ture and disturbance, have prevailed in various localities 
during all periods, and throughout all formations j from the 
first upraising of the earliest Primary rocks, to the most 
recent movements produced by existing Volcanoes. M. 
Elie de Beaumont has discovered probable evidence of no 
less than twelve periods of elevation, affecting the strata of 
Europe. 
Examples of the fractures and dislocations attending 
these movements, and producing faults, are represented in 
our Section by the lines designated by the letter 1. Some of 
these fractures do not reach to the present surface, as they 
affected the lower beds at periods anterior to the deposi- 
tion of more recent strata, which cover unconformably the 
summits of the earlier fractures. (See 1. 1^. P. P. 1®. P.) 
Basalt. 
A third series of Igneous Rocks is that which has formed 
dykes, and masses of Basalt and Trap, intruded into, and 
overlying formations of all ages, from the earliest Granites 
to the most recent Tertiary Strata. These basaltic rocks 
sometimes occur as Beds, nearly parallel to the strata, into 
which they are protruded, after the manner represented in 
the carboniferous Limestone of our Section, f. 2. More fre- 
quently they overspread the surface like expanded sheets 
of Lava. Our Section gives examples of Trap under all 
these circumstances. At f. 1. it intersects and overlies 
Primary strata ; at f. 2. f. 3. f. 4. f. 5. it stands in similar 
