Historic Landscape Characterisation

The Tanat Valley

THE NATURAL LANDSCAPE

The topography of the Tanat Valley is extremely diverse. It includes wild upland moorland areas, mostly in the north and west and generally between about 500-600m OD, steep hillsides on the valley sides, undulating hill country between about 200-250 metres, flat low-lying ground on the valley bottom, between about 100-200m OD. There is often a sharp and dramatic transition from valley bottom to mountain top, particularly in the west.

The Tanat Valley is broader in the west and terminates in the west in three narrow and deeply glaciated valleys cut into the Berwyns - Cwm Pennant with its offshoot Cwm Llêch, Cwm Rhiwarth, and Cwm Blowty. The entrance to a fourth valley - Cwm Maengwynedd - falls just within the historic landscape area, to the north of Llanrhaeadr-ym-mochnant. There are also a number of distinctive hanging valleys, including Cwm Dwygo to the south-west and Cwm Glan-hafon to the north-east of Llangynog.

The principal mountains are Mynydd Mawr, Moel Sych and Y Glogydd to the north, Bryn Ysbio and Cyrniau Nod to the west, Cyrniau, Dâs Eithin and Allt Tair Ffynnon to the south. One of the best vantage points is Tomen Cefn-côch motte from which practically the whole of the Tanat Valley can be seen, with the exception of the recesses of the western valleys.

The principal rivers and streams are Afon Tanat and its tributary Afon Goch, Afon Eirth (joining the Tanat at Llangynog), Afon Rhaeadr and Afon Iwrch (both joining the Tanat at to the south-east of Llanrhaeadr-ym-mochnant). There are a number of waterfalls including Pistyll Rhaeadr at the head of the Rhaeadr and Pistyll Blaen-y-cwm at the head the Tanat.

The solid geology comprises Ordovician mudstones, shales and slates of the Caradoc series with bands of acid lava and tuff and some intrusive fine-grained dolerites and rhyolites. Depths of over 150 feet of glacial and post-glacial gravel and clay have been recorded in the bottom of the valley during the course of mining at Llangynog.

Soils on the valley bottom comprise alluvial gley soils of the Conway series and brown earths of the Denbigh 1 and Rheidol series. Soils of the hill land comprises Cambric stagnogley soils of the Cegin series. The mountain soils are a combination of brown podzolic soils, largely of the Manod series, and ferric stagnopodzols of Hafren series.

In terms of land-use potential the uplands of the Tanat Valley are classed as Grade 5, the hill-slopes, western valleys and hill land are classed as Grade 4, with restricted areas of Grade 3 land on the valley floor between Llanrhaeadr-ym-mochnant and Llangedwyn.

Mochnant was renowned for its trees, but historical aspects of its wodland have yet to be studied in any detail. The rate at the native woodland was cleared is poorly documented though no doubt the poorer ground and particularly the steep-sided valleys and hillsides were the last to retain the woodland. The name of the cantref of Mochnant itself suggests a wooded environment suited to pigs. In the legend of Melangell prince Brochwel came across the virgin in a thicket, and her shrine is decked in foliage. The late medieval poet Llywarch ab Llywelyn spoke of the beautifully wooded environs of Mochnant - Am Fochnant cain amgant coedawg. In the early 14th century the greater part of parish of Llangedwyn is said to have continued to be wooded.

As late as the mid 19th century the tithe apportionments for parishes in the Tanat Valley abounded with place-name and field-name elements denoting woodland now lost, as in the following examples: holly (celynen) in Garthgelynen-fawr; birch (fedw) in Llety'r Fedw Ucha; willow (helig) as in Tyddyn yr Helig; bush or shrub (perth) as in Gwaith Gwr y Berth; wood (coed and gwydd) as in Coed Ffridd, Cae Gwydd Ucha, and Tanycoed.