Deadwood Gate, Not M/F
Wednesday 4 August 2021
Little Akatarawa Forest touches the much larger Akatarawa Forest1 along perhaps a 100 m length, which short length might fancifully be called a ‘gate’. The objective was to pass through this ‘gate’ and make our way to Deadwood, a spot height in the larger forest. Not really a sensible route (perhaps even ‘lunatic’ as a party member justifiably opined at one point) but still an interesting navigational challenge.
However, late morning, having just missed the gate, we gave up on Deadwood and adopted a simpler objective: get out of the forest before dark! The accompanying trace, Figure 1, indicates our decidedly haphazard progress. Two observations may be worth passing on.
Imagery versus topo map for on-screen navigation
The topo map indicates broad gentle ridges and spurs although kinks in the contours do suggest what is found on the ground: steep-sided gullies snaking across the ‘broad gentle’ areas2. The detail is just too fine to show with 20 m contours and having the topo map on screen is not as much help as one might imagine. It may show where you are (within ± 10 m) but won’t show the gully you’re in, and won’t really depict the lie of the land3. Aerial or satellite imagery indicating vegetation and lighting variations appears to be a better indicator of where a small gully or spur may be. Figures 2, 3 and 4 show our track near the ‘gate’ on the contour map, on WAMS and on Google imagery. NZtop50N, an Android app available at Google Playstore for $4.99, offers both contour map and Google Earth but zoom is limited. Georeferenced aerial photography for BP32, BP33 and other Wellington region maps is available on the LINZ website.
Screen-induced premature course correction
In the afternoon, returning to our start point, we picked up a good trail south along the ridge over .430. We knew descent required us to take the spur crest leading SE rather than one leading SW. So, when screens showed we were passing what looked like the turn-off, we turned off, headed down and then spent quite some time trying to find the route out! Quite likely the trail was going where we wanted to go, but local features had delayed its turn. This situation has arisen on other trips: trampers studying screens, seeking a turning point and not allowing the trail or pad to ‘show’ the best way.
1 Both forests, administered by Wellington Regional Council, are publicly accessible.
2 In addition the vegetation is dense and there are few vantage points from which the land ahead can be glimpsed, and navigation checked.
3 Further, Robin later downloaded a map showing Lidar-based 1 m contours. These showed that kinks in the 20 m contours do not always reliably indicate the position and run of gullies and spurs. Lidar maps are available at mapping.gw.govt.nz. The figures show our full route, 1, and a small section of the route on Topo50, 2, WAMS aerial, 3, and Google Earth,
- Party members
- Robin Chesterfield, Colin Cook (leader and scribe), John Dement, Jenny Mason, Sieny Pollard.