The result of this absence of precipice is,that there are no waterfalls in the front ranges and few in the back,and these few very insignificant as regards the volume of the water.In Switzerland one has the falls of the Rhine,of the Aar,the Giesbach,the Staubbach,and cataracts great and small innumerable;here there is nothing of the kind,quite as many large rivers,but few waterfalls,to make up for which the rivers run with an almost incredible fall.Mount Peel is twenty-five miles from the sea,and the river-bed of the Rangitata underneath that mountain is 800feet above the sea line,the river running in a straight course though winding about in its wasteful river-bed.To all appearance it is running through a level plain.Of the remarkable gorges through which each river finds its way out of the mountains into the plains I must speak when I take my dray through the gorge of the Ashburton,though this is the least remarkable of them all;in the meantime I must return to the dray on its way to Main's,although I see another digression awaiting me as soon as I have got it two miles ahead of its present position.
It is tedious work keeping constant company with the bullocks;they travel so slowly.Let us linger behind and sun ourselves upon a tussock or a flax bush,and let them travel on until we catch them up again.
They are now going down into an old river-bed formerly tenanted by the Waimakiriri,which then flowed into Lake Ellesmere,ten or a dozen miles south of Christ Church,and which now enters the sea at Kaiapoi,twelve miles north of it;besides this old channel,it has others which it has discarded with fickle caprice for the one in which it happens to be flowing at present,and which there appears some reason for thinking it is soon going to tire of.If it eats about a hundred yards more of its gravelly bank in one place,the river will find an old bed several feet lower than its present;this bed will conduct it into Christ Church.
Government had put up a wooden defence,at a cost of something like 2000pounds,but there was no getting any firm starting-ground,and a few freshes carried embankment,piles,and all away,and ate a large slice off the bank into the bargain;there is nothing for it but to let the river have its own way.Every fresh changes every ford,and to a certain extent alters every channel;after any fresh the river may shift its course directly on to the opposite side of its bed,and leave Christ Church in undisturbed security for centuries;or,again,any fresh may render such a shift in the highest degree improbable,and sooner or later seal the fate of our metropolis.At present no one troubles his head much about it,although a few years ago there was a regular panic upon the subject.
These old river channels,or at any rate channels where portions of the rivers have at one time come down,are everywhere about the plains,but the nearer you get to a river the more you see of them;on either side the Rakaia,after it has got clear of the gorge,you find channel after channel,now completely grassed over for some miles,betraying the action of river water as plainly as possible.The rivers after leaving their several gorges lie,as it were,on the highest part of a huge fanlike delta,which radiates from the gorge down to the sea;the plains are almost entirely,for many miles on either side the rivers,composed of nothing but stones,all betraying the action of water.These stones are so closely packed,that at times one wonders how the tussocks and fine,sweet undergrowth can force their way up through them,and even where the ground is free from stones at the surface I am sure that at a little distance below stones would be found packed in the same way.One cannot take one's horse out of a walk in many parts of the plains when off the track--I mean,one cannot without doing violence to old-world notions concerning horses'feet.
I said the rivers lie on the highest part of the delta;not always the highest,but seldom the lowest.There is reason to believe that in the course of centuries they oscillate from side to side.For instance,four miles north of the Rakaia there is a terrace some twelve or fourteen feet high;the water in the river is nine feet above the top of this terrace.To the eye of the casual observer there is no perceptible difference between the levels,still the difference exists and has been measured.I am no geologist myself,but have been informed of this by one who is in the Government Survey Office,and upon whose authority Ican rely.
The general opinion is that the Rakaia is now tending rather to the northern side.A fresh comes down upon a crumbling bank of sand and loose shingle with incredible force,tearing it away hour by hour in ravenous bites.In fording the river one crosses now a considerable stream on the northern side,where four months ago there was hardly any;while after one has done with the water part of the story,there remains a large extent of river-bed,in the process of gradually being covered with cabbage-trees,flax,tussock,Irishman,and other plants and evergreens;yet after one is once clear of the blankets (so to speak)of the river-bed,the traces of the river are no fresher on the southern than on the northern side,even if so fresh.
The plains,at first sight,would appear to have been brought down by the rivers from the mountains.The stones upon them are all water-worn,and they are traversed by a great number of old water-courses,all tending more or less from the mountains to the sea.How,then,are we to account for the deep and very wide channels cut by the rivers?--for channels,it may be,more than a mile broad,and flanked on either side by steep terraces,which,near the mountains,are several feet high?If the rivers cut these terraces,and made these deep channels,the plains must have been there already for the rivers to cut them.It must be remembered that I write without any scientific knowledge.
