The South Australian Naturalist. 
23 . 
be aptly compared with the successive crests and hollows produced 
by sea waves. In this way the Mount Lofty and Flinders ranges 
had been uplifted with deep valleys and undulating areas separ- 
ating the roughly parallel spurs and ridges. Evidences of this 
resistless earth movement were plainly visible in the strata of the 
quarries, which had been twisted into anticlines (A-shaped) and 
synclines (V-shaped), which could be readily traced. Veins of 
quartz were seen intruding into the layers in irregular directions 
This mineral fluid through intense heat and pressure pene- 
yates the strata, often carrying metallic ores, such as gold 
silver and copper. The quartz in the Mount Lofty quarries, how- 
ever, was of a very “hungry nature.’’ The presence of many 
quartz veins tends to reduce the value of the stone as building 
material, and for that reason one large block was left in the middle 
of the excavations. In her cyclopean masonry Nature employs 
four principal cements, namely clay, iron, quartz, and silica. The 
cementing agent in these quarries was mainly clay. Grains of 
quartz are often forced into softer sandstone or clay, and render 
them so hard that the hammer rings on the mass as on iron. 
For that reason this “quartzite” is shunned by quarrymen and 
stone masons. In the olden days the houses of Adelaide were 
built mainly of the hard blue clay-slates, which are almost everlast- 
ing. Now only the softer freestones and sandstones are accep- 
table to the builders, as being much easier to work, but the “lives” 
of the buildings are thereby considerably reduced. As the Mount 
Lofty and Flinders ranges represent a crest of the great earth 
waves, so the two gulfs are the hollows or depressions. The build- 
ing up of the fertile Adelaide plains by the silt and debris, slowly 
washed from the mountain chain in the long course of untold 
ages and deposited on what was once a seabed, was grahpically 
described. A spirited discussion arose as to the aesthetic merit 
or demerit of the “scars” left on the hill face by quarries. The 
doctor pointed out that Hilder, among other artists, considered 
that the brown, red, grey, or white patches harmoniously blended 
with the vivd green of meadow or vineyard and, by contrast, con- 
siderably heightened the effect of the purple distances. Nature, 
however, seems to take the earliest opportunity of repairing the 
damage, a fact which appeared from the dense growth of native 
nora an abandoned face. This wilderness, was, as the doctor 
remarked, a botanical museum, and our secretary was able to 
mentdy in this natural garden a few rare plants including Pulten- 
aea involucrata, P, acerosa, Etiphrasia Brozunil The vegetation 
01 these ridges comprises several desert types. Although abun- 
ant ram falls, the porous nature of the rock allows the water 
0 rapi y dram away, causing a drought in the midst of copious 
