Sunday, 4 January 2015

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

Ynys Tywyn (SH 571 385) - Double Sub-Twmpau addition   

There has been an addition to the 30-99m Twmpau list with this hill entering the caregory of Double Sub-Twmpau.  The name of the hill is Ynys Tywyn (SH 571 385) and it is situated at the end of the Cob in Porthmadog in north-west Wales.  

Ynys Tywyn has a small uppermost 20m contour ring on Ordnance Survey maps, but no spot height, and a recent survey with the Trimble GeoXH 6000 confirms that the hill is over 20m but under 30m in height and as it is the high point of an island that is now connected to Porthmadog by the Cob, and therefore its height is also considered to be its drop, it has been included in the Double Sub-Twmpau category.  The summit is crowned by a large flat rock and gorse bushes and has fine views over the Afon Glaslyn to the higher mountains of Eryri.

The full details for the hill are:

Cardinal Hill:  Moel Hebog

Summit Height:  21.8m (converted to OSGM15)

Name:  Ynys Tywyn

OS 1:50,000 map:  124

Summit Grid Reference:  SH 571 385

Drop:  21.8m (converted to OSGM15)

Ynys Tywyn (SH 571 385) is now confirmed as a Double SubTwmpau

For details on the survey that promoted this hill to Double Sub-Twmpau status please click {here}

Myrddyn Phillips (January 2015)

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