Friends of the Ochils Newsletter 19: Autumn 2001
The future's bright, the future's...?
IT'S BEEN THREE YEARS since a new map of the Ochils last appeared - the Harveys sheet of course - but now the Ordnance Survey's Explorer series has reached these shores. The Explorers are orange-covered and come in at a scale of 1:25000, thus re-placing the much-loved Pathfinder series (green-covered, also 1:25k, have been around for ever). A combination of larger sheet-size, occasional double-sided printing and weirdly-shaped boundaries mean that the 1366 Pathfinders have been reduced to a mere 300-odd Explorers as if by some magical origami trick.
The Explorer series has been nudging up from the south like some kind of cartographical weather front, and the whole country should be covered by 2003. Good progress is being made, with "only" the Highlands now remaining to be published. The local-Ochil sheets have appeared very recently, so while there hasn't as yet been scope for a proper assessment of their merits (this requires on-the-ground use over several months - test driving, as it were), there ought to be at least a brief preliminary discussion of what the mapmakers have been getting up to.
The main Ochils sheet is Explorer 366, a doublesided affair covering the Braco-Plean-Kincardine-Gleneagles rectangle on its eastern half and stretching as far west as Kippen and Callander on the flipside. The eastern FotO area is covered by the single-sided Explorer 369: Muckhart and Methven to Loch Leven and Perth.
Of course it's always good to get new maps of places you love, but the initial assessment of the Explorer series is that it looks to be something of a disappointment. "Revised 2001", the sheets say, but hold on - what's this, just south-east of Ben Cleuch on Ex366? It's the long-gone radio mast, that's what. Readers might recall precisely when this was removed - the late 1980s? - but there's been nothing more than the concrete plinth for many a day. Even the plinth can be hard to find (look left when heading up the eastern Ben Cleuch approach path, just at the point where the summit indicator pops into view); what is certain is that it shouldn't nowadays be mapped.
Ben Cleuch generally receives odd treatment on Ex366: the trig is there, as is the fence, but where is the aforementioned viewfinder (in situ since 1930) and the knuckle of summit rocks? Rocks and outcrops are often absent on these maps - the "Dollar top" of King's Seat Hill being another example - but at least these omissions are offset by arguably the best feature, the five-metre contour interval. Most OS maps stick with the traditional 10-metre gap, but the Ochils have long been granted more precise mapping. This is undoubtedly handy, as tight contouring defines steep ground very well. As FotO's webmaster and map expert Alan Dawson has pointed out in another context, you only have to compare the OS's crag-heavy Cuillin maps with the Irish OS's densely-contoured Reeks sheets to see which is the more useful on the ground.
Intense contouring does not necessarily imply accuracy, however. Take Wood Hill, where Ex366 gives the cairned summit a tiny 525m ring but then awards a larger (and presumably slightly higher) version to the grassy bump to the north, on the lip of the cleft that carves off the Millar Hill ridge. Now, unless my brain's levelling equipment has gone suddenly squint, there's no doubt that the cairn is the highest point - it appears to be some 5m or so higher than the "other" bump. Harveys gave the cairn a precise 526m, so if the bump is 525m minimum then the cairn must be closer to 530m. Either that or the bump is down towards 520m, in which case Ex366 has printed an imaginary contour.
Wood Hill is also home to a curious piece of renaming. The old Pathfinder applied the Wood Hill label to the lower slopes, calling the summit Rough Knowes - which I've never heard used. The Explorer, by contrast, has the subtly different Rough Knowles. Odd.
This small change suggests that there has at least been some upland revision on Ex366, and the "new" track up the east side of the Alva Glen duly appears. This is almost perverse, as the track has yet to make it on to any edition of Landranger 58, the main OS walking map for the area. So the lack of communication between departments appears to work both ways: the Landranger team knew about the non-mast but didn't tell the Explorer crew; vice versa for the track.
If Pathfinders 371 and 383 were indeed the templates for Explorer 366, then it's good to see that the mysterious trig symbol at grid ref 873983 above Craig Leith has been removed. This had puzzled me for ages - to the extent that I once rummaged through the rocks in search of concrete remains. Later, I noticed that other 1:25k sheets showed non-existent trig points, eg on Wetherlam in the Lakes, and shortly after that Ken Stewart came across a 1920s map positively festooned with trig symbols. This suggested that, prior to the 1936-62 triangulation (the one which gave us the familiar concrete trig points), all "normal" spot heights / survey stations were depicted by small triangles, and that various of these - eg Craig Leith, Wetherlam - lingered on larger-scale maps for decades afterwards.
The newsletter will return to this new wave of mapping over the next while. If anyone has any observations on the Explorers, either good or bad, do let us know. Longer term, it would be worthwhile submitting a list of errors and alterations to the OS, in hope that they feed them into the next revision process.