ABSENCE OE ROCKS. 
101 
in these latter years has furnished a subject of specu- 
‘‘ition to geologists, occupied us much during our journey 
Across the Llan 3s. I allude not to those blocks of primitive 
^oek which occur, as in the Jura, on the slope of iiinestone 
'Mountains, but to those enormous blocks of granite and 
®yenite, which, in limits veiy distinctly marked by nature, 
®Me found scattered on the north of Holland, (lermany, and 
he countries of the Baltic. It seems to be now proved, that, 
distributed as in radii, they came, at tlie time ot the ancient 
'■evolutions of our globe, from the Scandinavian peninsula 
^duthward ; and that they did not primitively belong to the 
pauitic chains of the llarz and Erz^eberg, which they 
approach, without, however, reaching their foot.* I was 
?di‘priscd at not seeing one of these blocks in tlie Lhuios of 
i Miiezuela, though these immense plains are bounded on the 
south by the .Sierra I’arima, a group of mountains entirely 
gi^anitic’ and exhibiting in its denticulated and often columnar 
peaks traces of the most violent destruction. N ortliward, the 
SMauitie chain of the Silla de Caracas and Porto Cabello are 
®oparated from the Llanos by a screen of mountains, that are 
, ohistose between Yilla de Cura and Parapara, and calcareous 
etw'een the Bergantin and Caripo. I was no less struck by 
.Ms absence of blocks on the banks of the Amazon. La 
^Mudamino affirms that from the Pongo de Manseriche to the 
‘ I’ait of Pauxis not tlie smallest stone is to be found. Now 
j.ie basin of the Eio Negro and of the Amazon is also a 
ip.MMo, a pl.ain like those of Venezuela and Buenos Ayres. 
iM difference consists only in the state of vegetation. The 
hlanos situated at the northern and southern extremities 
1 J^outh America are covered with gramina; they arc troe- 
savaimahs; but the intermediate Llano, that of the 
^j-Miazon, exposed to almost continual equatorial rains, is a 
Mick forest. I do not remember having heard that the 
of Buenos Ayres, or the savannahs of the Missourit 
t?- ^M'v Mexico, contain granitic blocks. The absence of 
c ^^Pj*®Moineuon appears general in the New World, as it 
fm*^^ 1 also is in Sahara, in Africa ; for we must not con- 
id the rocky masses that pierce the soil in the midst of 
+ Buck, Voyage en Norwiige, vol. i. p. 30. 
rrl ‘’i®''® onj isolated block* in North America northward of the 
6rc.it lakes ? 
