Doxsson AND SPEIGHT.—So-called ** Railroad” at Rakaia Gorge. 627 
The so-called ** Railroad” at Rakaia Gorge. 
By A. Duprey Dosson, M.N.Z.Soc.C.E., хәм К. Speicut, M.A., M.Sc., 
F.G.S., F.N.Z.Ins 
[Read before the Philosophical Institute of Canterbury, 4th April, er ; received by 
Editor, 14th April, 1923 ; issued separately, 28th August, 1924.] 
Plates 65, 66. 
ON pages 388-90 of Haast's Geology of Canterbury and. Westland (with plate), 
(Christchurch, 1879), there is a description of a peculiar landscape feature 
near Rakaia Gorge, locally known as the “ Railroad." Haast describes 
this in some detail, and ascribes its ео to mt -action, an explana- 
tion which presents serious difficulties—some of which Haast, no doubt, 
clearly recognized—so that the joint va aid of this paper have thought 
that the aia might very well be res . The conclusions they have 
-arrived at are the result of у-шу кай made separately on various 
occasions, poe jointly during three recent visits to the locali 
The feature referred to may be briefly described as resembling а road 
railway-cutting, hence its un (see Plates 65 and 66). It is three pis 
long, about five chains wide at its upper end, six crine: in its middle portion, 
and between six and seven—perhaps more—at its termination. It runs in 
5 nne pec bai ee the top of the high barik of the Rakaia near 
Bayfield H tead, where the river has excavated its bed to a depth 
d some 600 ft. i in ges um old lake-silts, o the northern slopes of 
Bryant's Hill, a rhyolite roche moutonnée near the lower end of the gorge. 
In this distanios it bac four old cede ead but ends at a slightly lower 
level as compared with that at which it s The first terrace is only 
about eight chains wide, but the features of ea “ Railroad ” are not marked 
at this point. They begin to be distinct on the top of the next terrace, 
where the depression may really be said to commence (see Plate 66), and 
from this to the end the ground falls about 40 ft. eos к. ке 
readings; but it must be remembered that as each successive terrace 
encountered there is a marked rise in the bed (Plate 65, fig. 3. d this is is 
also the case near the end as Bryant's Hill is approached, in the vicinity 
of which the terraces ppear. 
The depth of the күзүнөн below the level of the adjoining land- 
surface varies from about 20 ft. at a maximum on the top of the third terrace 
—it is 15ft. on the top ot the second terrace—to nothing on Bryant's Hill ; 
but it must not be assumed that the decrease is р since in one section 
the difference in level may be pronounced, while in any adjacent section it 
may be slight or absent. In general, the greatest depth appears to be just 
on the edge of a terrace, with a progressive diminution in depth as the 
difference on the top of the second terrace, Shek i is somewhat flat, and which 
