358 TRANSACTIONS OF SECTION C. 
Daly’s suggestion, however, taken into account with the history of Gondwana 
land, may explain the peculiar alignment of the heavy subterranean band, 
parallel to the Gangetic depression and parallel to the general trend of the 
peninsular tension-faults and fissures that followed the unloading of Gondwana- 
land and the heavy loading of the adjoining ocean bed along a band roughly 
parallel to the present Himalayan folds. 
R. 8S. Woodward objected that isostasy does not seem to meet the requirements 
of geological continuity, for it tends rapidly towards stable equilibrium, and the 
crust ought therefore to reach a stage of repose early in geologic time.*’ If the 
process of denudation and rise, with adjoining deposition and subsidence, 
occurred on a solid globe, this objection might hold good. But it seems to me 
that the break-up of Gondwanaland and the tectonic revolutions that followed 
show how isostasy can defeat itself in the presence of a sub-crustal magma 
actually molten or ready to liquefy on local relief of pressure. It is possible 
that the protracted filing off of Gondwanaland brought nearer the surface 
what was once the local level of no-strain and its accompanying shell of tension. 
The conditions existing in northern Gondwanaland before late Mesozoic times 
must have been similar to those in south-west Scotland before the occurrence 
of the Tertiary eruptions, for the crust in this region was also torn by stresses 
in the 8.W.-N.E. direction with the formation of a remarkable series of 
N.W.-S.E. dykes which give the one-inch geological maps in this region a 
regularly striped appearance. 
There is no section of the Earth’s surface which one can point to as being 
now subjected to exactly the same kind and magnitude of treatment as that to 
which Gondwanaland was exposed for long ages before the outburst of the Deccan 
Trap; but possibly the erosion of the Brazilian highlands and the deposition of 
the silt carried down by the Amazon, with its southern tributaries, and by the 
more eastern Araguay and Tocantins, may result in similar stresses which, if 
continued, will develop strains, and open the way for the subjacent magma to 
approach the surface or even to become extravasated, adding another to the 
small family of so-called fissure-eruptions. 
The value of a generalisation can be tested best by its reliability as a basis 
for prediction. Nothing shows up the shortcomings of our knowledge about the 
state of affairs below the superficial crust so effectually as our inability to make 
any useful predictions about earthquakes or volcanic eruptions. For many 
years to come in this department of science the only worker who will ever 
establish a claim to be called a prophet will be one in Cicero’s sense—‘ he who 
guesses well.’ 
MELBOURNE. 
FRIDAY, AUGUST 14. 
The following Papers were read :— 
1. The Geology of Victoria. By Professor Ernest W. Sxeats, D.Sc. 
2. Exhibition of a Series of Lantern Slides illustrating Desert Scenery 
and Denudation. By Dr. Jouannes Wavtuer. 
Every climatic region is characterised by a different type of disintegration 
and denudation of soft or softened rock by the agents of erosion. In the nival 
region a cover of snow protects the surface of the earth during a long period of 
the year. 
In the humid zone and also in the equatorial pluvial region the soil is over- 
** * Address to the Sect. of Mathematics and Astronomy of the Amer. Assoc.,’ 
1889. Smithsonian Report, 1890, p. 196. 
