Y Ceiliog Mawr (SH 594 598) - 200m Twmpau addition
There has been a new addition to the 200m Twmpau (thirty
welsh metre prominences and upward) hill list instigated through analysis of
LIDAR data by Aled Williams. The hill is
one that Aled first proposed as a prospective P30 Twmpau approximately two
years ago and it then waited to be Trimbled, but as it looked a daunting
prospect the Trimble surveyor shied away from his duties, and in the meantime
as LIDAR data is proving highly accurate I am using the data that Aled has
obtained.
The hill is situated in the Glyderau group of
hills with its Cardinal Hill being Y Garn (SH 630 595) and is placed in the
Region of North Wales (Region A, Sub-Region A1). The hill is
positioned above Llyn Peris which is to its south and the small community of
Nant Peris to its south-east and the town of Llanberis to its west. The hill is a part of the old Dinorwig Slate Quarries,
and can be accessed from tracks leading into the hill from the south-east and from
the west.
The hill is known locally as Y Ceiliog Mawr which
translates into English as the big
cockerel. I am thankful to Eric
Jones for the information relating to this name and the history of the hill which
comes from the following two passages on the Geograph website:
The Ceiliog Mawr is an igneous intrusion within the
Dinorwig Quarries. Several attempts were
made to remove the intrusion but a considerable section of it remains. "Ceiliog Mawr" means big cockerel.
Buildings associated with the Dinorwig HEP station
have been built around the foot of a slightly modified 'cockerel'. Three attempts were made in the past to
'slaughter the cockerel'. In 1896 Mr
Brinckman, the general manager, decided that the days of the cockerel were
numbered. On the day, the quarrymen were
invited to witness what "a real explosion was like". The cream of the Welsh aristocracy, and
dozens of cameramen, were also invited to watch the demise of the
cockerel. The fateful moment came and
the button pressed on the battery firer (the only occasion in the history of
the quarry for a battery firer to be used).
A huge pall of smoke emerged from the rock. When it cleared, Y Ceiliog Mawr stood
unscathed. A visit by the Prince and
Princess of Wales in May 1902 was an excuse for another go, this time using two
tons of explosive, only to leave more egg on the managers' face. Finally, in 1905, 10 shafts were dug into the
outcrop at a cost of £437-12-2 and explosives set at the bottom of each. Again, only a few loose rocks were
dislodged. Ever since, the Ceiliog Mawr
has been an icon of Dinorwig Quarry.
Current Ordnance Survey 1:50,000 and 1:25,000
mapping does not give this hill any ring contours, as is the norm for areas of
land that have been quarried. The hill
is of interest (and quite daunting) as it is only now listed as a 200m Twmpau through
the quarrying activities of past years, as it has been left as a stone monolith
separated from its connecting bwlch by over 37m of vertical height.
Aled’s analysis of LIDAR data gives the hill the
following details:
Y
Ceiliog Mawr
Summit
Height: 220.3m
Summit
Grid Reference: SH 59467 59848
Bwlch
Height: 182.8m
Bwlch
Grid Reference: SH 59538 59823
Drop: 37.5m
Therefore, the 220.3m LIDAR data produced for the
summit position at SH 59467 59848, and
the 182.8m LIDAR data produced for the bwlch position at SH
59538 59823 is sufficient for this hill
to be included in the list of 200m Twmpau hills with 37.5m of drop, and
therefore Y Ceiliog Mawr is included in the listing of Twmpau which will be
updated accordingly.
The full details for the hill are:
Cardinal Hill: Y Garn
Summit Height: 220.3m
(LIDAR data)
Name: Y Ceiliog
Mawr
OS 1:50,000 map: 115
Summit Grid Reference: SH 59467 59848
Drop: 37.5m (LIDAR
data)
My thanks to Aled for supplying the details of his
LIDAR analysis of this hill.
 |
| Y Ceiliog Mawr - the new 200m Twmpau. Photo © Aled Williams |
To view an old and a relatively recent photograph of Y Ceiliog Mawr {here} {here}
Myrddyn Phillips (December 2016)
No comments:
Post a Comment