Mapping Mountains - Hill Reclassifications - 30m - 99m Twmpau

Ynys Glog (SH 596 398) and Ynys Berfedd (SH 599 398) - 30-99m Twmpau additions   

There have been three new Welsh island P30 hills recently discovered.  These additions to the 30-99m Twmpau list were found by Aled Williams through map study and local knowledge of the area, with two of these hills accepted automatically to the listing of Twmpau hills and with the other hill entering the Twmpau list through surveying with the Trimble GeoXH 6000.

The two hills automatically accepted in to the 30-99m Twmpau list are Ynys Glog (SH 596 398) and Ynys Berfedd (SH 599 398).  Whilst the other hill is named Ynys Hir (SH 566 396) which was confirmed as a P30 through surveying with the Trimble GeoXH 6000.  

Aled considered the hill at SH 566 396 and its adjacent hill at SH 566 398 which is also known as Ynys Hir as suitable candidates for surveying with a high chance of promotion to the P30 ranks, and considered that the uppermost 20m ring contour given to both hills on the Ordnance Survey enlarged mapping hosted on the Geograph website was incorrect and a misrepresentation of their actual height.

A note from Aled:

Two New P30 Hills

Analysis of OS enlarged mapping on the Geograph website confirms two P30 hills that are absent from both the '30-99m Twmpau' list by Myrddyn Phillips (2004) and the 'Tumps' list by Mark Jackson (2009). I bring this information to the attention of the authors.

Name: Ynys Glog
Height: 40.6m (converted to OSGM15)
Drop: 32.7m (converted to OSGM15)
Grid Reference: SH 59647 39826


Name: Ynys Berfedd
Height: 42.9m (converted to OSGM15)
Drop: 36.1m (converted to OSGM15)
Grid Reference: SH 59943 39865


Aled Williams (03/02/2014).

The discovery of new P30’s is not a rarity, but what is unusual is that each of these hills was once an island that is now landlocked in the area known as Traeth Mawr, this is near to Aled’s home in Porthmadog.  Subsequently all of these hills have been surveyed using the Trimble GeoXH 6000 and their respective results are given above.

For more detail of the Trimble survey that promoted Ynys Hir to 30-99m Twmpau status click {here} 

A post by Aled on the land known as Traeth Mawr and its many small islands is due for publication in the Guest Contributor page on the Mapping Mountains blog in March. 

Aled Williams at the summit of Ynys Hir (SH 566 396)

Myrddyn Phillips (February 2014)