32 Physical Geography. 
Marl soils occur on the Wanganui coastal plain, in some parts of Hawkes‘ 
Bay and locally in various places. Sandy soils are frequent on and near the 
coast, and arise either as blown sand from the shore or from the disintegration 
of soft sandstone: They are also frequent on the gravel plains. 
Alluvial loams form the bulk of the soil of lowland valleys in both 
Islands. 
Humus soils are of widespread distribution. They occur at all altitudes 
and vary from a thin surface-layer to peat-deposits, 12 m deep, as in the Chatham 
and Lord Auckland Islands. The rain forest climate is eminently favourable for the 
production of humus. The subantarctic and wet high mountain climates favour 
the formation of raw humus and peat. 
Volcanic soils, though of wide occurrence in many parts of the New Zealand 
region, are generally local and limited in extent. They are specially fertile and 
the distinction between the vegetation of volcanic and “gumland” soils in Auck- 
land is striking. The other soils mentioned above need no special comment here. 
5. The Geological History of New Zealand. 
Although there are rocks in New Zealand of Archaean and Palaeozoic age 
nothing is known as to the geographical conditions of their deposition. New 
Zealand, as a permanent land, dates only from the Mesozoic period. It was 
then, according to MARSHALL, "That the great series of folded stratified rocks 
of which the main mountain-ranges are constituted were deposited during a 
long continuous period, lasting almost throughout the Mesozoic age, when the 
present position of the country was on, or near the shore-line of a great con- 
tinent” (rgı2b. in Author’s preface), which “stretched far to the westward and 
probably united New Zealand with Australia” (1g12a: 35). 
Br \t the close of the Trias-Jura period the Mesozoic sediments were folded 
> and | greatiy elevated, the land N extending to New Caledonia or 
en rd, to the CI athams i in E. E. and to en jaans, or 
Rn include all the present Su ielands,. except perhaps . Macquaı 
. Kermadecs. This was the period of the elachal re already eu IE 
continued active, ‚Ruapehu, burst forth at this time 
a 
Eu 
