1884] On the Evidence that the Earth's Interior is Solid. 771 
- thenatural heat of the rocks themselves to cause their passage into 
the liquid state ? 
It has been claimed with apparent justice that the simple de- 
_ pression of any portion of the earth’s crust into the still liquefied 
portion of its interior, would tend to cause the base of the 
_ depressed portion to re-liquefy through the greater heat to which 
it would be then subjected to, thus making the re-fusion the nat- 
_ lal result of the earth's contraction. 
| Itappears to the writer that so far as any evidence now exists 
_fgarding the earth’s interior, it is allowable to assume its present 
‘liquid state. A state that in his judgment accords better with 
ahi of petrography than any other assumption that has been 
itis true that if the materials of the earth’s interior were solid, 
o but could be liquefied by diminution or increase of pressure, this 
a ion would perhaps be consonant with what is now known 
ofthe internal structure of rocks, especially the partial dissolving of 
the olivine of basalts, the hornblende of the andesites, the quartz 
X the thyolites, etc. One of the greatest difficulties in the way 
a thi Supposition is to understand why the same lava should 
uce different crystals when it was in the interior from those 
~ Sd on the exterior of the earth. 
_ Itis difficult to see how, if the earth is solid, that any relief 
Pressure could take place otherwise than from the crushing 
gether of the overlying rocks, the tearing up of these from the 
‘Ying ones, and elevating them into the air; that is, the 
Sol: n Pressure would come from an elevating instead of a 
te Process. In truth it would seem that eruptions and 
he an building or elevations arose rather from the sinking of 
large, Causing smaller ones adjacent to rise, or, as an- 
ocean 1 by Dana, the highest border is on the side of the greatest 
of 
It would seem that elevation followed subsidence, in- 
~ OL subsidence following elevation, If this is the case, it is 
“ito explain how subsidence could be brought about first 
*alid globe. 
