The Welsh P15s - Introduction to the Mapping Mountains List

 

The Welsh P15s 

All Welsh hills with 15m minimum prominence

Introduction to the Mapping Mountains List

 

In early May 2019 the compilation of The Welsh P15s was finally completed.  This list took over 8 years to compile, with approximately a year dedicated to the hills at or above 500m in height and the remaining hills below 500m being compiled from 2012 onwards.

The criterion for The Welsh P15s is all Welsh hills that have 15m minimum drop, irrespective of their height.  With an accompanying sub list taking in all Welsh hills that have 14m or more and below 15m of drop.

The list was introduced via articles published on Mapping Mountains on the 10^th May 2019 and on the UKHillwalking website.

At the time of completion The Welsh P15s comprised:

5,431 P15 hills with 435 P14 subs.

 

As with many listings of hills, the contents therein can be used to create sub sets of hills, and the further down the scale of either height and/or drop one goes, the more sub sets of lists can be created.  The Welsh P15s is no different with some of the lower prominence hills being extracted and prioritised for other lists. 

It is always my intention when listing hills to include sufficient detail to give merit to the inclusion of each hill.  This can be time consuming, especially for numerical data where GNSS receivers and LIDAR analysis are now available giving accurate height, and also for hill name data when each is researched using a variety of sources including local enquiry, Ordnance Survey maps; both contemporary and historical and the Tithe maps; with the latter especially important for lower heighted hills.

Therefore, listing The Welsh P15s in Google Doc format via an excel spreadsheet will be a time consuming process.  The prioritised lower prominence hills extracted from The Welsh P15s for other hill lists mainly relate to the height bands at and above 400m.  Therefore, the groupings of hills that will appear in the foreseeable future on Mapping Mountains will in the main be for those whose highest hill is below 400m in height.

As the research required for each hill is time consuming, future hill listings will appear when assessed in the main with either LIDAR and/or a Trimble GeoXH 6000 survey.  Prior to the most recent LIDAR coverage for Wales the first Group where place name and numerical data for each hill had been completed is for the Mynydd Twr group of hills.  At the time of publication this Group comprised 172 P15s and 26 P14 subs, with a further eight hills listed that have been deleted from the original compilation of this list.

Qualifying hills will appear on Mapping Mountains when fully researched and complete.  These will appear on an ad-hoc basis with no regimented time scale for publication.

 

The Mapping Mountains list consists of the following:

 

Group:  Each hill is listed by Group, with each Group following topography that was determined by Aled Williams and Myrddyn Phillips.  The name of each Group appears under the highest hill in its topographical area.

Name:  This is considered the most appropriate name for the hill, based on local usage where this is known.  Names have been researched from a variety of sources including; local enquiry, contemporary and historical Ordnance Survey maps and for many of the lower heighted hills from the Tithe map.  The name used does not always correspond to contemporary Ordnance Survey map spelling and/or composition or the name may not appear on any map.  Where an appropriate name is not forthcoming for the hill, the Point (for example; Pt. 66.8m) notation is used rather than making up a name that has no local or historical evidence of use.

Summit Height (m):  This gives the summit height in metres of the hill above Ordnance Datum Newlyn (ODN), often referred to as sea level.  Where a height is quoted to a decimal place it implies the summit has been surveyed by GNSS receiver (survey grade GPS) or obtained from LIDAR analysis (these heights may not match current Ordnance Survey map heights), with the heights produced by GNSS receiver converted to OSGM15.  Where a ‘c’ (circa) appears preceding the summit height it means this has been estimated from contour interpolation.

 

1:50,000 Map:  This column gives the number or numbers of the 1:50,000 Ordnance Survey Landranger map that the summit of the hill appears on.

 

1:25,000 Map:  This column gives the number or numbers of the 1:25,000 Ordnance Survey Explorer map that the summit of the hill appears on.

 

Summit Grid Reference:  This is the ten figure grid reference for the summit position of the hill.  This has either been produced by an accurate survey via GNSS receiver, from LIDAR analysis, a map spot height, hand-held GPS via DoBIH or for interpolated heights by a centralised position in an uppermost contour ring.

Summit Grid Reference extracted from:  Details of where the ten figure grid reference for the summit of the hill was derived.

 

Drop (m):  This column details the prominence of the hill, otherwise known as drop or re-ascent.  The drop is the height difference between the summit and the lowest connecting bwlch to the higher parent peak along the watershed.  Where the letter ‘c’ (circa) appears preceding the drop value it signifies there is no spot height, surveyed height or a height ascertained via LIDAR for either the summit or more usually, the bwlch, therefore a part of the drop value has been estimated from contour interpolation.

Bwlch Grid Reference:  This is the ten figure grid reference for the bwlch position of the hill.  This has either been produced by an accurate survey via GNSS receiver, from LIDAR analysis, a map spot height, hand-held GPS via DoBIH or for interpolated heights by a centralised position in an uppermost contour ring.

Bwlch Grid Reference extracted from:  Details of where the ten figure grid reference for the bwlch of the hill was derived.

 

Bwlch Height (m):  This gives the bwlch height in metres of the hill above Ordnance Datum Newlyn (ODN), often referred to as sea level.  Where a height is quoted to a decimal place it implies the bwlch has been surveyed by GNSS receiver (survey grade GPS) or obtained from LIDAR analysis (these heights may not match current Ordnance Survey map heights), with the heights produced by GNSS receiver converted to OSGM15.  Where a ‘c’ (circa) appears preceding the bwlch height it means this has been estimated from contour interpolation.

Notes:  This column gives additional information relating to the hill, including headings for Place Name Information, Numerical Data and Listing History, with the latter relating to prominence based hill lists.

 

Access:  The Welsh P15s lists all hills in Wales that have 15m minimum drop (14m minimum drop including the sub list).  This is a scientific exercise in documenting hills that meet set criterion.  If wanting to visit any of these hills, please abide by any legal restriction and if unsure ask permission to visit from the landowner.

 

Risks:  Hill walking is an activity with risks and dangers, both natural and man-made.  Please only attempt hills within your capabilities and fully appraise yourself of, and prepare for, the possible risks before attempting to visit any hill.  Participants in these activities should be aware of and accept these risks, and be responsible for their own actions and involvement.

Thanks:  Thanks are given to the people who submit 10 figure grid references to the Database of British and Irish Hills (DoBIH) and for DoBIH making these available for public use.

 

 

Mapping Mountains downloadable list in Google Doc format