Y creigiau sydd i’w gweld yn Nyffryn Dyfrdwy Beth yw RIGS? Gwibdaith trwy’r gorffennol Rocks you may see in the Dee Valley Gall Safleoedd Geoamrywiaeth o Bwysigrwydd Rhanbarthol (Regionally Important Geodiversity Sites) fod yn unrhyw safleoedd a gaiff eu gwarchod Taith ddaearegol ar y trên oherwydd eu pwysigrwydd addysgol, ymchwil, hanesyddol neu esthetig. Creigiau gwaddod Creigiau trwy Ddyffryn Dyfrdwy, Yn wreiddiol, roedd y creigiau hyn yn haenau o dywod, llaid neu gwaddod What are RIGS? weddillion creaduriaid môr a gafodd eu claddu a’u cywasgu a’u troi’n Sedimentary Regionally Important Geodiversity Sites (RIGS) are any sites that are dywodfaen, yn garreg laid neu’n galchfaen. rocks protected for their educational, scientific historical or aesthetic value. Steaming through the past Sedimentary Rocks Ca r r e g l a i d Mu d s t o n e A geological rail trail These rocks were originally sand, mud or the remains of sea creatures Beth ydy geoamrywiaeth? that have been buried, compacted and formed sandstone, mudstone and limestone respectively. Geoamrywiaeth yw’r amrywiaeth o greigiau, ffosilau, mwynau a of the Dee Valley, Llangollen phriddoedd, ynghyd â’r proseseu naturiol sy’n llunio’r dirwedd. Ty w o d f a e n What is Geodiversity? Meini dyfod Sa n d s t o n e Cafodd y meini hyn eu cludo gan iâ ac maent yn estron i’r mannau lle y Geodiversity is the variety of rocks, fossils, minerals landforms and gorweddant heddiw. Fe’u gwasgarwyd dros y tir wrth i’r iâ ddadmer tua soils together with natural processes that shape the landscape. 17,000 o flynyddoedd yn ôl, ar ddiwedd yr Oes Iâ ddiwethaf. Maent yn ddefnyddiol gan eu bod yn dynodi cyfeiriad llif yr iâ.

Me i n i d y f o d Grwpiauˆ RIGS? Erratics Er r a t i c s Gall unrhyw aelod o’r cyhoedd a chanddo ddiddordeb mewn These rocks were transported by ice and are foreign to the places in which they are found today. They were dropped when the ice melted about cadwraeth treftadaeth y ddaear ymuno â grwpˆ RIGS. Mae’r grwp yn 17,000 years ago at the end of the last Ice Age. Erratics are useful for dewis y safleoedd sydd wedyn yn cael eu gwarchod gan awdurdodau indicating the direction of ice flow. lleol. Gyda chydweithrediad perchenogion, datblygir rhai safleoedd at ddefnydd addysgol neu gan y cyhoedd. Creigiau metamorffig Creigiau metamorffig RIGS groups Yn wreiddiol, creigiau gwaddod neu igneaidd oedd y rhain ond cawsant eu newid neu eu metamorfforeiddio gan wres a/neu wasgedd. Dros gyfnod o Metamorphic Any member of the public with an interest in Earth heritage filiynau o flynyddoedd trodd llaid, a ddyddodwyd yn wreiddiol ar wely cefnfor rocks conservation may join a RIGS group. The groups identify sites that dwfn, yn garreg laid ac yna’n llechfaen dan ddylanwad cywasgiad dwys. Ll e c h i  sÊl b l w m are then protected by the local authority. With the co-operation of the Sl a t e w i t h l e a d Metamorphic Rocks f l a s h i n g landowners, some sites are developed for educational or public use. These rocks were originally sedimentary or igneous rocks that have been changed, or metamorphosed, by heat or pressure. Slate, originally laid down as mud in deep oceans, compacted over millions of years into mudstone was then compressed into slate. Os hoffech ymuno â grwp RIGS yn yr ardal hon, cysllter â: If you would like to join a RIGS ˆgroup in north east , please contact: Craig artiffisial Creigiau artiffisial o wneuthuriad dyn o wneuthuriad Cynthia Burek, Department of Biological Sciences, Pan nad oedd cerrig parod neu addas ar gael, aeth pobl ati i gynhyrchu dyn cerrig gwneud ar ffurf briciau neu goncrit. Defnyddiwyd clai Rhiwabon, ger University of , Parkgate Road, Chester. CH1 4BJ Man-made Wrecsam, i gynhyrchu briciau coch adnabyddus Rhiwabon. Defnyddid clai Ebost / Email: [email protected] Sir Amwythig i gynhyrchu’r briciau glas cadarn. artificial rock Br i c i a u c o c h www.ukrigs.org.uk Man-made or Artificial Rocks Rh i w a b o n a b r i c i a u www.newrigs.org g l a s Sir Am w y t h i g When natural rock is not suitable or available, humans made rock in the Ru a b o n Re d b r i c k www.geologists.org.uk form of bricks or concrete. Here, clay from near Wrexham, has a n d Bl u e www.llangollen-railway.co.uk been used to make typical Ruabon Red bricks and the blue bricks are made Sh r o p s h i r e b r i c k from Shropshire clay which makes particularly strong bricks. Mae Cyngor Cefn Gwlad Cymru yn cefnogi sefydlu Safleoedd Geoamrywiaeth o Bwysigrwydd Rhanbarthol Metel The Countryside Council for Wales supports the Gwneir defnydd helaeth o fetelau megis plwm a haearn ar Reilffordd establishment of Regionally Important Geodiversity Sites Llangollen. Mae mwyn plwm, galena, sydd i’w gael yng nghalchfaen Sliperi gogledd-ddwyrain Cymru, wedi cael ei gloddio ers yr Oes Efydd. Câi haearn, a ddefnyddir i gynhyrchu cledrau, ei smeltio ym Mrymbo, ger concrit ©NEWRIGS Wrecsam. Defnyddir plwm i selio toeau. Concrete rail Lluniau: J. Malpas a R. Roberts Photography J. Malpas & R. Roberts ties

Metal a c h e l d r a u h a e a r n Metals such as lead and iron are used extensively on this railway. Lead w i t h i r o n r a i l s ore, galena, was mined from the limestone of north-east Wales since the Bronze Age. Iron is used for the rails and was smelted at Brymbo near Wrexham. Lead is used to seal the roofs.

In some areas the mudstones have been compressed so much, Development shaped by geology forming good quality slate, which is still quarried locally. The remains of these slate workings can be seen high up on the sides The geology of the Dee Valley has had a strong influence on how of the valley. The west-east flow of the River Dee here is partly humans have used the area. Local slate from the quarries in the Dee controlled by two of faults in the rocks, namely the Llangollen and Valley has been exported around the world and is still being quarried faults (see cross section). at the Horseshoe Pass. The limestone of the was also quarried and the disused quarries are now used for leisure activities During the last Ice Age the valley was filled by ice fed from the such as walking and climbing. The canal, the railway and later the mountains of Snowdonia and the surrounding higher ground, A5 were built on the relatively flat valley floor to move goods and scraping away at the sides of the valley to form a U-shape. As well people to and from the area. The geological heritage of the area is as its erosive action, the ice would have carried material eastwards well served by several long distance walks - the Dee Valley Way, the from Snowdonia. The material left behind when the ice melted is North Berwyn Way and Offa’s Dyke Path. made up of till (ground-up rock), sand, gravel and erratics.

Datblygiad a luniwyd gan ddaeareg Mae daeareg Dyffryn Dyfrdwy wedi dylanwadu’n fawr iawn ar sut Golygfa o’r awyr o Ddyffryn Dyfrdyw yng nghyffiniau Llangollen - Awyrlun © Pixaerial mae pobl wedi datblygu’r ardal. Cafodd llechi o chwareli Dyffryn Aerial view of the Dee Valley at Llangollen - Aerial photograph © Pixaerial Dyfrdwy eu hallforio i bedwar ban byd ac maent yn cael eu cloddio hyd heddiw ym Mwlch yr Oernant. Câi calchfaen Eglwyseg ei Tirwedd a luniwyd gan ddaeareg gloddio hefyd ac erbyn hyn defnyddir yr hen chwareli ar gyfer gweithgareddau hamdden megis dringo a cherdded. Cafodd y Rhwng Corwen a Llangollen mae creigiau’r fro, sef tywodfeini a gamlas, y rheilffordd ac, yn ddiweddarach, ffordd yr A5 eu hadeiladu cherrig llaid Silwraidd, i’w gweld yn aml yng ngwely’r afon. Yn ar lawr lled wastad y dyffryn er mwyn cludo nwyddau a phobl ddiweddarach yn eu hanes, cafodd y creigiau hyn eu gogwyddo a’u i’r ardal ac allan ohoni. Mae modd gwerthfawrogi treftadaeth ffawtio gan symudiadau daear. Wrth gael eu cywasgu, cawsant eu ddaearegol yr ardal drwy ddilyn nifer o lwybrau cerdded hir – Llwybr plygu ar ffurf y llythyren U. Dyffryn Dyfrdwy, Llwybr Gogledd y Berwyn a Llwybr Clawdd Offa. Arhosfa Glannau Dyfrdwy Deeside Halt Mewn rhai mannau cafodd y cerrig llaid eu cywasgu’n enbyd, gan ffurfio llechfaen o ansawdd da a gaiff ei gloddio hyd heddiw. Gellir Croestoriad daearegol ar draws Ddyffryn Dyfrdwy gweld y chwareli hyn yn uchel ar lechweddau’r dyffryn. Mae dyffryn Geological cross-section across the Dee Valley afon Dyfrdwy, y gellir ei olrhain o’r gorllewin tua’r dwyrain, wedi’i DO/SW reoli’n rhannol gan ffawtiau Llangollen a Llandysilio (gweler y Afon Dyfrdwy croestoriad). GD/NE Mynyddoedd y Berwyn River Dee Yn ystod yr Oes Iâ ddiwethaf roedd y dyffryn yn llawn iâ a gâi Mountains Llangollen ei fwydo gan rewlifau a oedd yn llifo o fynyddoedd Eryri a’r Gwely’r ucheldiroedd amgylchynol cyfagos ac yn creu dyffryn ar ffurf y ‘Slabiau’ Eglwyseg ‘Grut Melinfaen’ llythyren U. Yn ogystal ag erydu’r tir, byddai’r iâ wedi cludo meini ‘Slab’ horizon ‘Millstone’Grit’ o Eryri tua’r dwyrain. Mae’r deunydd a adawyd ar y tir wedi i’r iâ Dinas Brân ddadmer yn cynnwys til (cerrig a chreigiau mâl), tywod a graean, a Calchfaen meini dyfod. Silwraidd Carbonifferaidd Carboniferous Landscape shaped by geology limestone Ordofigaidd Between Corwen and Llangollen the underlying geology is Silurian sandstones and mudstones, which are often seen in the river bed. Later mountain building events have compressed these rocks, Ffawt faulting and tilting them (see cross-section). This compression folded Ffawt Llangollen Ffawt Llandysilio the rocks into a U-shape. Fault Fault Fault Yr Oes Iâ Diwethaf ,AST)CE!GE 1UATERNARY ALLWEDD KEY Map o Ddyffryn Dyfrdwy SGARP Pen y Glôg Chwarel Quarry EGLWYSEG Map of the Dee Valley ESCARPMENT Slate Quarry Miliynau o Rheilffordd The slate tips of flynyddoedd -ILLIONSOF yn ol Cwaternaidd 2 Railway CHWAREL Y BERWYN YEARSAGO the Pen y Glôg  4 Afon Dyfrdwy QUARRY (Penarth) Slate ERTIAR Y River Dee Quarry are above us Gwaddodion afon ac iâ on the south side rydyddo l River and ice deposits of the valley. Slate Calchfaen Carbonifferaidd FRON quarrying produces huge amounts of waste which was FAWR

Carboniferous limestone tipped over the hillside. During the late 19th and early #%./:/)#

Y Cyfnod T Carreg laid Silwraidd MYNYDDOEDD LLANTYSILIO 20th Century, pioneering women geologists, Gertrude Silurian mudstone MOUNTAINS 10 Elles, Ethel Woods and Margaret Crosfield, investigated COED these quarries. Their efforts resulted in the important

CAINOSÖIG DÔL HYRDDYN work called British Silurian Graptolites, published in 1918. FAWR 6 CARROG Gertrude Elles found here one of the earliest land plants, it is about 420 million years old, because of this; Pen y 5 8 9 Glôg Quarry is protected as a Site of Special Scientific BERWYN DINAS twnnel 3 BRÂN Interest (SSSI). GLYNDYFRDWY tunnel 1 4 2 7 CHWAREL PEN Y GLOG Meini dyfod rhewlifol QUARRY MYNYDDOEDD Y BERWYN LLANGOLLEN Cafodd y clogfeini sydd i’w gweld yn y nentydd a’r MOUNTAINS 1 afon eu cludo yma gan iâ yn ystod yr Oes Iâ ddiwethaf. G/N CHWAREL ‘SLABIAU’ Marwolaeth Wrth i’r iâ o Eryri symud dros y tir, cludai feini tua’r %XTINCTIONOF y Deinosoriaid GLANNAU DYFRDWY $INOSAURS 65  DEESIDE ‘SLAB’ QUARRY dwyrain. Yn ystod y symudiad hwn, cafodd y meini eu #RETACEOUS treulio a’u llyfnhau, 0 1km cyn cael eu gwasgaru dros y tir wrth i’r iâ Cretasig ddadmer tua 17,000 o Yr olygfa o’r orsaf Berwyn Station flynyddoedd yn ôl. Yr ochr draw i’r afon, i’r de o Langollen, cwyd The station is built of yellow brick probably from north east mynyddoedd y Berwyn. Dyddodwyd y cerrig llaid Silwraidd Wales but the road and rail bridges are built of the same stone as Glacial Adar Cyntaf y naddwyd y mynyddoedd hyn ohonynt mewn basn cefnforol &IRST"IRDS

Llangollen Station. Erratics *URASSIC dwfn iawn tua 420 miliwn o flynyddoedd yn ôl pan orweddai Berwyn Station is at the head of the Dee Gorge where the valley The boulders seen in Cymru yn hemisffer y de. Cawsai llechfeini’r ardal eu cloddio narrows. This is the third bridge here as the previous two were the streams and river ers blynyddoedd lawer. Mae modd gweld y chwareli ar -%3/:/)# Jwrasig washed away during violent flooding in 1870 and 1928. were transported here by ice during the last Ice Age. As lechweddau’r bryniau uwchlaw Dyffryn Dyfrdwy. the ice moved over the land from Snowdonia, it carried Tua’r gogledd, mae Castell Dinas Brân, safle bryngaer o’r Oes rocks with it. This movement of ice wore down and Haearn a chastell dafeiliedig Pen draw’r twnnel

MESOSÖIG rounded the rocks, which were deposited when the ice yn dyddio o’r 13g., yn bwrw Y tu hwnt i’r twnnel cawn ein hunain yn rhan o Safle o Ddiddordeb melted about 17,000 years ago. ei drem dros Langollen. Gwyddonol Arbennig (SoDdGA) Afon Dyfrdwy. Hysbyswyd y rhan hon o Saif y castell, hen gadarnle afon Dyfrdwy am ei diddordeb daearegol a biolegol. Dyma un o’r mannau 4RIASSIC tywysogion , ar gorau yng ngwledydd Prydain i astudio’r modd y mae afon yn datblygu. Gorsaf Glyndyfrdwy frig cerrig llaid Silwraidd a Awgryma presenoldeb hen lannau a cherlannau uwchlaw lefel bresennol Y maes chwarae (lle ceir maes pêl-droed ac arwydd Triasig gloddiwyd i godi’r bryngaer, y afon Dyfrdwy fod iddi hanes hir a chymhleth ac ei bod hi, ar adegau, yn datgan ‘Dim gêmau pêl’!) oedd yr iard nwyddau ar gyfer castell a’i ragfuriau. wedi tyrchu’r tir yn rymus iawn. Yma, inclein y lein fach, sef tramffordd Nant y Pandy i Foel Fferna mae’r afon wedi erydu ystum mawr ac a Chwareli Slabiau View from station iddo ochr allanol serth ac ochr fewnol Glannau Dyfrdwy. Across the River mwy graddol a nodweddir gan hen O’r fan yma câi llechi gerlannau a glannau. eu hallforio i bedwar 248 Dee to the south, above  Llangollen, are the ban byd. Mae llwybr 0ERMIAN Berwyn Mountains. These Exit of Tunnel hyfryd yn dilyn Nant are Silurian mudstones At the end of the tunnel we y Pandy ac yn ymuno deposited in a very deep ocean about 420 million years enter part of the River Dee Site of â Llwybr Gogledd y Permaidd ago when Wales lay in the southern hemisphere. These Special Scientific Interest (SSSI). Berwyn. rocks have been quarried for slate for many years. The This length of the River Dee is notified for its geological and biological

interest. This section is one of the best places in Great Britain to #ARBONIFEROUS quarries can be seen in the hills up above the Dee Valley. Glyndyfrdwy Station study how a river develops. The presence of banks and terraces above The playground (football pitch with sign saying ‘No Overlooking Llangollen, to the north, is Castell Dinas Bran, the current river level suggests that the history of the river is long and ball games’!) was the goods yard for the narrow gauge the prominent ruined Iron Age and 13th Century complex and that, at times, it cut down with greater vigour. The river railway incline, the Nant y Pandy Tramway to Moel Fferna of the princes of Powys Fadog. The castle occupies has eroded a large meander (loop) with a steep outer bend and a more and Deeside Slab Quarries. Slate from here was exported an outcrop of Silurian mudstone which was quarried to gradual inner bend with old terraces and fossil river banks. Carbonifferaidd all around the world. Coedwigoedd Cyntaf build the hillfort, castle and ramparts. &IRST&ORESTS There is a beautiful walk up Nant y Pandy, which joins the $EVONIAN Gorsaf Carrog North Berwyn Way long distance walk. Gorsaf Llangollen Yn wahanol i’r gorsafoedd eraill, codwyd gorsaf Carrog o gerrig Codwyd yr orsaf a’i muriau cynhaliol o Dywodfaen llaid Silwraidd tywyll, lleol. Tywodfaen Cefn, carreg a oedd yn haws i’w Golygfeydd o darren Eglwyseg Cefn a gloddiwyd yn ardal Wrecsam. Dyddodwyd y naddu, yw’r conglfeini a chilbyst y ffenestri. Ar y to, gwnaed defnydd o 0!,!%/:/)# Defonaidd tywodfaen Carbonifferaidd hwn ar ffurf traeth pan oedd dri math o lechen, a ddeuai o chwareli gogledd Cymru a rhai lleol. Mae’n Ar eich siwrnai cewch sawl cipolwg o darren neu sgarp trawiadol Eglwyseg. Mae’r calchfeini hyn tua 350 400 Cymru yn y trofannau, tua 320 miliwn o flynyddoedd yn ôl. bosibl y cafodd y plwm sy’n selio’r toeau, y ffenestri bae a’r simneai

3ILURIAN miliwn o flynyddoedd oed ac fe’u ffurfiwyd pan orweddai’r Ar y to ceir llechi porffor, o ei gloddio’n lleol oherwydd yr oedd mwyngloddio plwm yn ddiwydiant tir sydd bellach yn Gymru yn y trofannau. Yn ystod y cyfnod PALEOSÖIG Lanberis yn ôl pob tebyg. pwysig yng ngogledd Cymru. Ym Mwynglawdd, ger Wrecsam, câi plwm hwn roedd y rhan fwyaf o ogledd Cymru dan ddyfroedd môr Codwyd y caban signalau ei gloddio o’r cyfnod cynhanes hyd 1914. trofannol bas a chynnes a oedd yn llawn creaduriaid morol: o friciau coch Rhiwabon, Silwraidd cwrelau, braciopodau (cregyn môr), crinoidau (lilïau’r môr) a gâi eu cynhyrchu ger Carrog Station a thrilobitau prin iawn. Ers hynny, cafodd y creigiau eu codi Wrecsam, a’r manylion o Carrog Station, in contrast to a’u gogwyddo gan symudiadau daear grymus, a’u cerfio gan /RDOVICIAN friciau peirianyddol glas the others we have seen, is built of rewlifau. Mae sgri Sir Amwythig. Câi’r briciau local, dark Silurian mudstone. The wedi ymgasglu wrth eu cludo i’r ardal ar y quoins (corner stones) and window odre’r darren, wrth rheilffordd. frames are pale, Cefn Sandstone which was easier to shape. The i brosesau rhewi- Ordofigaidd dadmer ar ddiwedd Llangollen Station: decorative roof uses three different

yr Oes Iâ ddiwethaf #AMBRIAN The station and retaining walls are built of Cefn slates, from local and North Wales chwilfriwio a disodli Sandstone quarried from the Wrexham area. The Cefn quarries. The lead that seals the roofs, bay windows and chimneys, may have been mined locally as lead mining was an important filiynau o ddarnau Sandstone is Carboniferous in age and was deposited in industry in North Wales. Minera near Wrexham mined lead from onglog o’r clogwyni a beach setting when Wales was in the tropics some 320 prehistoric times until 1914. calchfaen. million years ago. Cambriaidd The roof is purple slate, probably from Llanberis. The 545 Mae’r rheilffordd wedi’i Views of Eglwyseg Escarpment  signal box was built from Ruabon Red bricks, made near hymestyn i arhosfa On your train journey you will see glimpses of the 02% Wrexham, and the detail is Shropshire Blue engineering Bonwyn erbyn hyn dramatic Eglwyseg Escarpment. These limestones are brick. These materials would have been brought to Railway now extended to about 350 million years old and were deposited during Llangollen by the railway. #!-"2)!. Bonwm Halt the Lower Carboniferous Period when the area that is now Wales lay in the tropics. At this time, much of North Gorsaf y Berwyn Dychwelyd / Return Wales was under a warm, shallow tropical sea which Codwyd yr orsaf hon o was teeming with marine animals; corals, (shellfish), crinoids (sea lilies) and rare . Since friciau melyn a gynhyrchwyd Chwarel lechi Pen y Glog yng ngogledd-ddwyrain Mae tomennydd Chwarel lechi Pen y Glog (Penarth) i’w gweld then the land has been uplifted and tilted by huge Cyn – Gambriaidd Cymru, yn ôl pob tebyg, fry ar ochr ddeheuol y dyffryn. Roedd gwaith cloddio’r llechfaen yn Earth movements and carved by ice. Along much of the ond adeiladwyd pontydd y esgor ar bentyrrau anferth o gerrig rwbel a gafodd eu gwaredu dros y escarpment scree has accumulated at the foot of the ffordd a’r rheilffordd o’r un limestone cliffs. Millions of angular fragments have been garreg â gorsaf Llangollen. llechweddau. Yn ystod blynyddoedd olaf y 19g. a blynyddoedd cynnar 3400 yr 20g. archwiliwyd y chwareli hyn gan dair daearegwraig arloesol, sef dislodged from the escarpment through freeze-thaw  Creigiau Hynaf Saif gorsaf y Berwyn ym processes since the end of the last Ice Age. /LDEST2OCKS Prydain mhen gorllewinol y ceunant Gertrude Elles, Ethel Woods a Margaret Crosfield. Esgorodd eu gwaith IN"RITAIN y mae afon Dyfrdwy yn llifo ar astudiaeth bwysig yn dwyn y teitl British Silurian Graptolites, a drwyddo. Dyma’r drydedd gyhoeddwyd yn 1918. Yn y fan yma y cafodd Gertrude Elles hyd i un o’r bont i’w chodi yma. Sgubwyd ymaith y ddwy bont flaenorol planhigion tir cynharaf, sydd tua 420 o filiynau o flynyddoedd oed, ac o’r 4600 herwydd dynodwyd Chwarel Pen y Glog yn SoDdGA.  Ffurfiad y Byd adeg llifogydd mawr 1870 a 1928. %ARTH&ORMS