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A NOTE ON FORMER KAURI DAM SITES IN THE
T A B L E MOUNTAIN A R E A
by B.W. Hayward*
In the rugged Coromandel Peninsula remnants from the gold mining days
often overshadow the spectacular relics from the kauri milling era, which, due to
old age, the natural elements and human interference, are rapidly disappearing.
•Geology Department, University of Auckland.
198
Because many of the former kauri dam sites will be unrecognisable in less
than a decade, a permanent record of those that exist today in the watersheds
around Table Mountain is considered to be worthwhile. The seventeen dam sites
recorded in Fig. 1 were all located during a geological survey of the area between
January and May 1971 (B.W. Hay ward, 1971). Over 80% of the creeks in the
Table Mountain area were traversed and although only seventeen sites were
located, debris of dressed planks in a number of stream beds testify the former
existence o f many more.
These kauri dams were built in extremely inaccessible and rugged positions
and were constructed from logs, often up to 20 metres in length. The typical
dam built in the Table Mountain area was known as the Stringer, Flume and
Loose Gate Plank Dam (Reed, 1964). The basal portion consited of two to
six logs (often up to one metre square) set across the stream and sunken into
slots cut into the stream base. These were the sills that were planked to form
the flume, and are often the only portion of the dam still in place today.
Commonly, even these have disappeared, and only remnant slots in the stream
bank indicate their former position.
The longest log used in construction was the main stringer, jacked into
position high above and right across the stream. This formed the top of the gate
and held the loose gate planks and sloping rafters, on which the carefully
squared wing planks were fixed, to form the main structure of the dam (fig. 2).
Fig. 2: Sketch of a Stringer, Flume and Loose Gate Plank Dam.
The dam sloped upstream at between 3 0 ° and 7 0 ° and was supported behind
by backlegs.
In three dams (10, 15 and 16) the main stringer is still in place over the
stream. More often the planking on the rafters of the wings is still in position
high up on the strain banks as in dams 9, 12 and 14.
It is rare to find a dam with most o f the structure, including planking and
gate planks, still intact. The only complete dam found by the author within
the Table Mountain area was dam 16 (on a tributary to the east of Table
Mountain).
In the 1920's, sixty-four dams are alleged to have existed in the headwaters
of the Kauaeranga River (Bert Collins in Reed, 1964), and from the number
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located in several of the streams visited, together with evidence for more unlocated dams, it would seem that this number is not excessive.
Variation in dam size was not great in this area; the highest dam seen would
have been 18 metres high (15) whilst the widest was 30 metres across (9),
although the size of the watercourse on which they were constructed was
extremely variable. The remnants o f one dam (7) were found high on the slopes
of Table Mountain, in a rock watercourse, which, in A p r i l 1971, was little more
than a trickle of water.
Invariably the dams were built where the stream had a solid rock basement
and preferably where the banks had solid rock at a shallow depth. Dam 2,
appears to have its eastern side built over recent unconsolidated conglomerates.
The presence o f a second dam (3), 100 metres downstream, may indicate that
the first dam leaked and a second was built where such a porous bank did not
exist.
The rock type, as long as it was consolidated, appears to have had little
effect on the position of dams. They have been found dug into Minden Rhyolites
(4 and 5), rhyolitic breccias, lapillistones and lapillituffs (1, 8, 9, 13, 15 and 17),
freshwater
sediments
(11), Omahia Andesites (6 and
7), Beesons Island
Volcanics' andesitic flows and breccias (2, 3, 10, 12, and 14) and even recent
consolidated conglomerates (16) (B.W. Hayward, 1971).
The dams are always sited where the banks of the stream are sufficiently high
to contain a reasonable amount of water and usually where there is at least a
moderate stretch behind for water accumulation, although sometimes this could
have been no more than 40 or 50 metres (15). In a number of instances,
especially on small streams, the dams are situated immediately downstream of a
fork, in order to gather water from the combined watersheds (5, 9, 10 and 11).
In most cases the dam has been built near the top of the largest waterfall in a
stream. Presumably this was done so that the greatest impetus of water, immediately after release, was available to carry the logs over the falls and further downstream. Extreme examples are dam 17, situated at the top of 60 metre high
falls, the lower Wainora dam (12) at the top of a 30 metre vertical fall and
the upper Waiwawa dam (4) at the top of 40 metres of cascading falls. When not
sited directly above waterfalls, the dams are often at the heads of steep-sided,
narrow gorges, such as dams 9 and 15, Moyle's Stream dam (14) and the lower
Waiwawa dam (5).
Notwithstanding all these considerations, it seems that the dams were
ultimately sited in positions which enabled the removal of the greatest number
of kauri logs with the least effort.
Another remnant in the area from the two periods of kauri milling (1880's
and 1920's) is the old tramway up the Kauaeranga Valley, recognisable in the
raised embankment beside the picnic area on the Whangaiterenga Stream; the
steep tramway which descended from the plateau at the headwaters of the
Atuatumoe Stream, bypassing the high Billygoat Falls, can still be recognised by
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its deep cutting on the spur to the south of the stream and by the collapsed
viaduct, a little higher on the plateau. Other relics include several of the booms
used to catch the logs as they were driven down the Kauaeranga by the waters
released after the dams were tripped. These can still be seen in the floodplain of
the Kauaeranga River, between the Wainora and Whangaiterenga Stream
junctions.
The majority of old tracks used by the lumberjacks are now overgrown and
lost, but a few have been relocated by the N . Z . Forest Service and cleared for
use as access tracks. One example is the "steps in rock" track, that was cut to
provide an access route for supply teams o f packhorses from the lower
Kauaeranga River to above the Kauaeranga Gorge. Another track that has been
relocated is the one crossing the lowest point in the main Coromandel Divide,
500 metres west of Table Mountain, probably the main packhorse route between
the Kauaeranga and Waiwawa milling areas.
Felled logs are prevalent throughout the area, lying rotting on spurs,
stranded and buried in bouldery stream beds or jammed between the rocky
sides of gorges and waterfalls.
REFERENCES
Hayward, B.W.
1971
The geology and eruptive history of the Table Mountain
region. Unpublished BSc (Hons) thesis, University of Auckland.
Reed, A . H .
1964
T h e New Story of the K a u r i . " A . H . and A.W. Reed, Wellington. 363 pp.
E R R A T A : T A N E , V O L . 17.
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correction
proteaceous and not unlike
proteaceous though unlike
Table 6. Plagusia capensis
Cyclograpsus
insularum