Friday 10 May 2019

The Welsh P15s


The Welsh P15s

All Welsh hills with 15m minimum prominence



Wales was the first of the constituent countries of Britain to be mapped down to 30m prominence and I am proud of my contribution toward this.  This contribution consisted of the Welsh P30 hills below 500m in height and these were published during 2002 and 2003 with an accompanying P20 sub-list on Geoff Crowder’s v-g.me website.  However, the accompanying sub-list was not standard as it did not use interpolated height, took Ordnance Survey spot heights as fact and only included hills that once surveyed stood a chance of entering the main P30 list. 

After these P30 lists were published I set about compiling a P15 list to the Welsh hills at or above 500m in height.  This list later became co-authored with Aled Williams.  However, I knew soon after its compilation that it would form one part of a greater list, with this larger list consisting of all Welsh P15s and by doing so this would also standardise the P20 sub-list accompanying the P30s.

The Welsh P30 and Welsh 500m P15 lists were reliant upon Ordnance Survey 1:25,000 paper mapping.  Since the original compilation of these lists times have changed, with varied mapping resources now available online for any budding hill list compiler including historic Six-Inch and One-Inch maps.  However, it was not until the advent of an Ordnance Survey map hosted on the Geograph website that my aim to map the whole of Wales down to P15 could start in earnest.  This map is known as the Vector Map Local and entitled the Interactive Coverage Map on the Geograph website, and its advantage over other publicly available maps is the inclusion of many spot heights that are inclusive just to this map.  For list compilers it seemed their Christmas’, birthdays and any other special occasion had all arrived at once!

When compiling the Welsh P30s I listed by 100m height bands, and by hill group from north to south, and did likewise for their P15 counterparts.  Therefore, after the Welsh P15 hills at or above 500m in height were completed my next P15 height band were the 400m hills.  For me, using 100m height bands is a natural progression and having employed this when originating the Welsh P30 lists I knew that listing in this manner made the scale of the task manageable, as if the overall task was considered my patience and enthusiasm for this venture would have been seriously tested.

I was made aware of the Ordnance Survey mapping on the Geograph website by Trevor Littlewood in March 2012, with Jim Bloomer also showing me the same mapping during a visit to his house.  This mapping proved invaluable and gave impetus toward listing the 400m P15s, and when Mark Trengove proposed a Europeaklist booklet to the Welsh 400m P30s in January 2013, I wanted to fully revise this list, taking a systematic approach involving checking the details in the larger 400m P15 list from scratch and only cross referencing against my previous work after each group of hills was completed.  This resulted in a fully revised list entitled Y Pedwarau – The 400m Hills of Wales and the creation of the second element of the greater Welsh P15s list.

When compiling the Welsh P15 hills at or above 500m in height I created an accompanying P14 sub-list.  I contemplated creating a P12 or even P10 sub-list, but realised this would be too reliant upon interpolation and would also increase the work substantially.  The concept of a P14 sub-list was therefore also employed as I started on the other height bands of P15 hills.

It was during compilation of the Welsh 300m P15s that I developed a routine of map checking and noted detail, which I find, if repeated, becomes standard practice.  However, these routines are seldom planned, and only develop out of a necessity and are a natural consequence of the time consuming and detailed cataloguing of hill list compilation; these routines can then be refined as progress is made.  In the process of completing the Welsh 300m P15s I had also fully revised the list that would later become known as Y Trichant – The 300m Hills of Wales and also standardised its accompanying P20 sub-list and found many new P30s by doing so.

As the Welsh P15 list progressed downward in 100m height bands an ever increasing number of new P30s were found, the details of which were fed in to my P30 lists and also passed on to the wider hill bagging community via the RHB and latterly the Tump forum.

The listing of the Welsh P15s include an appropriate name for the hill and its connecting bwlch (if known), their heights and ten figure grid references and the hill’s drop value.  Prior to listing the Welsh 200m P15s no dates were recorded for when each page full to busting of numerical and place-name information was completed.  This was rectified for the 200m hills with the first page for the Ynys Môn group completed on the 16.11.13 and the last group which I then referred to as Bryniau Cymoedd completed on the 28.08.14.  The Welsh 200m P15s proved to have the greatest number of hills of any 100m height band within Wales.

During the latter part of 2013 I invested in a Trimble GeoXH 6000 and activated the Mapping Mountains site, and much of my hill related activity was now directed through these media.  With my attention now concentrated on surveying and writing articles for Mapping Mountains progress on the remaining height bands of Welsh P15s inevitably slowed.

I started compilation on the 100m height band of Welsh P15s on the 03.10.14.  When the Mynydd Hiraethog group of hills was finished I opted to compile the hill groups within the 15-99m height band of hills immediately after completing their 100m counterparts.  This dual height band form of compilation remained during the next 3½ years until full completion.

When compiling the original Welsh P30s I found the 30-99m height band to be the most difficult to list and envisioned the same would apply to their P15 counterparts.  The main reason for this is that lower heighted contours stretch for greater distances and by doing so are more difficult to follow, resulting in adjoining bylchau being more difficult to pinpoint compared to their higher heighted counterparts, and it was the 15-99m height band of Welsh P15s adjoined to the Ynys Môn group of hills that proved the most difficult of all to compile as the land taking in this group is relatively low in height but also large in area.

During the latter stages of compiling the Welsh P15s the Ordnance Survey 5m contouring on the OS Maps website became available online, and this mapping was then used to cross reference against the mapping on the Geograph website.

The other major resource that became available during this overall compilation is LIDAR (Light Detecting & Ranging).  This has revolutionised list compilation in ways that only independent surveyors can match, and all from the comfort of a chair in front of a laptop screen; the times they are indeed a’ changing!

The 100m height band of Welsh P15s was finally completed on the 27.04.19, closely followed by their 15-99m counterparts on the 07.05.19.  When I listed the last hill and completed the whole of Wales mapped down to P15 (mapped down to P14 with the inclusion of the subs) I looked at the online mapping I had been studying and with a relieved smile on my face closed the tab on my laptop and filed the last page of hill details in their folder.
 
The Welsh P15 list has taken me over 8 years to complete, with about a year dedicated to the hills at or above 500m in height and the remaining height bands being compiled from 2012 onwards.

The bi-product of listing down to P15 with accompanying P14 subs has resulted in the discovery of many new P30 hills, it has standardised their accompanying P20 sub-list and also resulted in a Double Sub list that now accompanies the Welsh Twmpau P30 list. 

Although these are important bi-products of the Welsh P15s, it is this larger list that holds forth as its overall number of 5866 hills is vast compared to any other previous listing of Welsh hills, with the inclusion of over 2,800 hills never before listed and classified. 
     

The current totals for the height bands as they were compiled are:

P15s at or above 500m:  631 hills with 26 P14 subs. 

400m P15s:  872 hills with 68 P14 subs.

300m P15s:  1083 hills with 78 P14 subs.

200m P15s:  1138 hills with 88 P14 subs.

100m P15s:  995 hills with 94 P14 subs.

15m – 99m P15s:  712 hills with 81 P14 subs.


The Welsh P15s comprise 5431 hills with 435 P14 subs.


Myrddyn Phillips (May 2019)






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