5 ^ 
]:ositions by the i)revailing winds. The rock represents in their 
opinion, old sand dunes that have l^eeii in large part consolidated. 
Owing to the variability in composition from place to place, 
the whole of the sands of these old dunes have not been con- 
solidated into the hard coastal limestone, although the latter rock 
outcrops so widely that in maj^ping the country fairly definite 
boundaries must be given to the area in which the limestone pre- 
dominates, and in this way it must be saparated from those other 
dimes which appear so far to have entirely esca])ed consolidation, 
or almost so. 
This irregularity of conversion of the dunes into limestone 
is rather to be expected than to be wondered at, when the process 
of consolidation, namely, the solution from the sands themselves 
and the redeposition of carbonate of lime, and the diiferetit 
characters of the sands, which are i)artly calcareous and partly 
almost wholly siliceous, arc considered. The process may be 
regarded as a more oi less continuous one from the time of its 
commencement to the present day, and it is still going on. Concur- 
rently with this consolidating ])rocoss. the limestone is being re- 
duced again to sand by atmos]dicric agencies, and these two 
antagonistic forces have no doubt been at work from the time when 
consolidation first commenced, which would probably soon follow 
the formation of the dunes. 
There is no definite evidence as to the age of the older dunes, 
but judging from their distribution they ivere formed subsequent 
■ o the de])osition, and uplift of the Plantagent marine beds. 
The remaining rocks of the district belong to the recent period 
and comprise the sands of the jmesent forming dunes of the coast 
and of the beaches and bars of the present seas, together with the 
fine silt (including diatomaceous earth of Crassmere and else- 
where) now filling the lakes and swamps of the low-lying portions 
of the district. They need not be further mentioned here. 
PHYSIOGRAPHY. 
KJX'EXT 1)ISPLA(’EMKXTS OF THE STBAXD LINE. 
There is evidence in the Albany district of three comparatively 
recent — geologically speaking — displacements of the strand line, 
'['he first (jKjsitive) ot these three is that of the submergence of 
the old eroded granite land surface, upon which the Plantagenet 
marine beds rest. As those beds now form a wide-spread plain of 
marine sedimentation, the ocean, on the displacement referred to, 
must have stretched as far north as the Stirling Range, and also 
to the east and west of /Vlbany, the eastward extension covering 
