Pwllheli to Blaenau Ffestiniog Gas Pipeline
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Pwllheli to Blaenau Ffestiniog Gas Pipeline Archaeological excavations carried out by Gwynedd Archaeological Trust for Wales & West Utilities Ymddiriedolaeth Archaeolegol Gwynedd Gwynedd Archaeological Trust Wales & West Utilities Pwllheli to Blaenau Ffestiniog Gas Pipeline Introduction In 2011 Wales & West Utilities replaced a major gas pipeline from Pwllheli to Blaenau Ffestiniog, Gwynedd, North Wales. As well as being an engineering project Wales & West Utilities had to mitigate any potential damage to archaeological sites along the route so it also became a VLJQL¿FDQWDUFKDHRORJLFDOSURMHFWZLWK*Z\QHGG$UFKDHRORJLFDO7UXVWFRPPLVVLRQHGWRFDUU\ RXWWKHDUFKDHRORJLFDOZRUN7KHSURMHFWUHYHDOHGVHYHUDOEXUQW PRXQGV GDWLQJ IURP WKH ODWH 1HROLWKLFWRWKHHDUO\PHGLHYDOSHULRGV2WKHUGLVFRYHULHVLQFOXGHG D %URQ]H $JH FUHPDWLRQ EXULDO,URQ$JHSLWVDQGDQ,URQ$JHVKHOOPLGGHQDPHGLHYDOFRUQGULHUDVPLWKLQJVLWHDQGD SRVVLEOHPHGLHYDOFDXVHZD\ 7KHZHVWHUQHQGRIWKHURXWHUDQDORQJWKHJHQWO\XQGXODWLQJODQGRQWKHVRXWKHUQVLGHRIWKH /OǔQ3HQLQVXOD7KHQWKHURXWHUDQLQODQGWRWKHKHDGRIWKHZHVWHUQEUDQFKRI7UDHWK0DZU ZKLFKZDVIRUPHUO\WKHWLGDOHVWXDU\RIWKH$IRQ*ODVO\Q7KHPRXWKRIWKLVHVWXDU\ZDVEORFNHG in 1813 by an embankment, known as the Cob, so that the land behind the barrier could be drained and claimed for agriculture. $IWHUWKHWRZQRI3RUWKPDGRJWKHSLSHURXWHFURVVHGWKH$IRQ*ODVO\QDQGRYHUWKHVSXURI ODQGRQZKLFK3HQUK\QGHXGUDHWKZDVEXLOW7KHURXWHGHVFHQGHGRQWRWKHÀRRGSODLQRIWKH$IRQ 'Z\U\GDQGIROORZHGWKHÀDWUHFODLPHGIDUPODQGXSWKHULYHUYDOOH\SDVW0DHQWZURJ:KHUH WKHYDOOH\QDUURZVWRWKDWRIDPRXQWDLQVWUHDPWKHSLSHURXWHKHDGHGQRUWKDFURVVTXLWHVWHHSO\ undulating upland country to Blaenau Ffestiniog, set in the heart of the mountains of Snowdonia. 40 50 60 70 50 50 Blaenau Ffestiniog 40 40 Porthmadog Criccieth Pwllheli Cardigan Bay Harlech 30 SH 40 50 60 Map of the pipe route (in red) with land over 200m in brown &RS\ULJKW*Z\QHGG$UFKDHRORJLFDO7UXVW 01 Wales & West Utilities Pwllheli to Blaenau Ffestiniog Gas Pipeline 0ethodology 'XULQJWKHZRUNV*$7DUFKDHRORJLVWVPRQLWRUHGWRSVRLOVWULSSLQJDORQJWKHSLSHOLQHHDVHPHQW DQGWKHH[FDYDWLRQRIWKHSLSHWUHQFK$Q\SRWHQWLDODUFKDHRORJLFDOIHDWXUHVRUGHSRVLWVZHUH LGHQWL¿HGDQGHYDOXDWHG:KHUHWKHVHZHUHVLJQL¿FDQWWKH\ZHUHIXOO\H[FDYDWHGDQGUHFRUGHG Recording included photographs, scaled plans and detailed notes. Monitoring topsoil stripping Initial investigation of potential archaeology Excavation and recording 02&RS\ULJKW*Z\QHGG$UFKDHRORJLFDO7UXVW Wales & West Utilities Pwllheli to Blaenau Ffestiniog Gas Pipeline 2QFHWKH¿HOGZRUNZDVFRPSOHWHGWKHVLWHUHFRUGVDQG¿QGVZHUHVWXGLHGDQGDUHSRUWZULWWHQ 7KHSRVWH[FDYDWLRQVWXG\LQFOXGHGDQDO\VLVRIFKDUUHGSODQWUHPDLQVZRRGVWRQHDUWHIDFWVDQG obtaining radiocarbon dates. Worked wood from a burnt mound near Pentrefelin A full report has been produced with detailed descriptions and specialist reports and this is DYDLODEOHIRUFRQVXOWDWLRQDWWKH*Z\QHGG+LVWRULF(QYLURQPHQW5HFRUGDQGFDQEHGRZQORDGHG IURPWKH*$7ZHEVLWH ZZZKHQHEFRXN 7KH¿QGVDUHKHOGDW*Z\QHGG$UW*DOOHU\DQG0XVHXP%DQJRUDQGWKHGLJLWDODQGSDSHU UHFRUGVDUHKHOGE\WKH5R\DO&RPPLVVLRQRQWKH$QFLHQWDQG+LVWRULF0RQXPHQWVRI:DOHV Aberystwyth. Graph showing the calibration of a radiocarbon date Two of the very few worked Àints found SF22 Soil 0 50mm micromorphology samples Drawing of a utilized pebble &RS\ULJKW*Z\QHGG$UFKDHRORJLFDO7UXVW 03 Wales & West Utilities Pwllheli to Blaenau Ffestiniog Gas Pipeline BXUQW0RXQGV %XUQW PRXQGV DUH KHDSV RI EXUQW KHDWFUDFNHG VWRQH DVVRFLDWHG ZLWK SLWV IRU KROGLQJ ZDWHU 7KHVHVLWHVDUHYHU\FRPPRQLQQRUWK:DOHVEXWIHZZHUHH[FDYDWHGLQGHWDLOKHUHEHIRUHWKH SUHVHQWFHQWXU\([FDYDWLRQHOVHZKHUHKDVVKRZQWKDWWKH\ZHUHXVHGWRKHDWODUJHTXDQWLWLHVRI ZDWHUE\GURSSLQJKRWVWRQHVLQWRDSLWRIZDWHU7KHUHDVRQVIRUKHDWLQJZDWHULQWKLVZD\DUH not known, though suggested uses for the hot water pits include cooking, bathing, saunas, dying, fulling and beer making. Few burnt mounds were SUHYLRXVO\NQRZQIURPWKH/OǔQ 3HQLQVXODEHFDXVHWKH\KDYHEHHQ OHYHOOHGE\SORXJKLQJDQGFDQ RQO\EHIRXQGE\H[FDYDWLRQ7KLV project found 11 burnt mounds RU SRVVLEOH PRXQGV VHYHUDO concentrated around Pentrefelin. 7KHPRXQGVDUHRIWHQDVVXPHG WREH%URQ]H$JHLQGDWH %& EXWDV¿QGVDUHUDUHIURP these sites radiocarbon dates are needed. As more sites are dated it has become clear that they were XVHGRYHUDYHU\ORQJSHULRG $QH[WHQVLYHGDWLQJSURJUDPPH was carried out on the mounds found in this project and it was GLVFRYHUHG WKDW PDQ\ GDWHG IURP WKHHQGRIWKH1HROLWKLFSHULRGDERXW%&2QHZDVXVHGLQWKHPLG%URQ]H$JHLQDERXW %&EXWPRVWVXUSULVLQJO\RQHVLWHQHDU3HQWUHIHOLQZDVGDWHGWRWKHWKFHQWXU\$'(DUO\ PHGLHYDO'DUN$JHEXUQWPRXQGVDUHYHU\UDUH RUUDUHO\VXI¿FLHQWO\ZHOOGDWHGWREHLGHQWL¿HG DQGWKLVLVDUHPDUNDEOHSLHFHRIHYLGHQFHWKDWLQGLFDWHVWKHWUDGLWLRQFRQWLQXHGIRUPLOOHQQLD A burnt mound exposed near Pentrefelin (right) with the pit that was excavated beneath it (above). This site dated to the 7th century AD but looks just like the late Neolithic and Bronze Age mounds 04&RS\ULJKW*Z\QHGG$UFKDHRORJLFDO7UXVW Wales & West Utilities Pwllheli to Blaenau Ffestiniog Gas Pipeline Next to Pentrefelin was a large area FRYHUHGZLWKEXUQWVWRQHV8QGHUWKLV ZHUHVHYHUDOSLWV0RVWZHUHVLPSOH rounded pits dug into the clay, but one was DUHFWDQJXODUWURXJKWKDWPD\KDYHEHHQ lined with wood. All the pits are thought WRKDYHKHOGZDWHUWKDWZDVKHDWHGDVKRW VWRQHVZHUHDGGHG7ZRVKDOORZJXOOLHV PD\KDYHFDUULHGZDWHURYHUWKHVLWH/LNH many burnt mounds this site lay next to DVWUHDPZKHUHZDWHUFRXOGKDYHEHHQ obtained. 7KH ZRRG XVHG WR IXHO WKH VLWH ZDV collected nearby and included alder that VHHPVWRKDYHEHHQOHIWWRVHDVRQWRKHOS it burn better. 7KLVVLWHZDVXVHGLQWKHODWH1HROLWKLF from before 2500 BC, through to the HDUO\%URQ]H$JHXQWLODERXW%& ,WZRXOGSUREDEO\KDYHEHHQXVHGLQVKRUW N episodes, each related to digging and XVLQJDSLW7KHVLWHVHHPVWRKDYHEHHQ 05m abandoned for centuries then used again DURXQG%&ZKHQWKHUHFWDQJXODU trough was used. stream Site near Pentrefelin repeatedly used for burnt mounds. The grey represents the burnt mound spreads, which overlay natural channels (grey dashed lines); drains (black dashed lines) ran through the site. It is not yet clear what the burnt mounds were XVHGIRU&HUWDLQO\DORWRIZDWHUPXVWKDYHEHHQ heated and probably kept boiling for some time. 2QHVXJJHVWLRQLVWKDWIRRGZDVFRRNHGLQWKHSLWV but there is rarely any bone or other rubbish left on the sites. Bathing, washing clothes or fulling cloth KDYH DOO EHHQ VXJJHVWHG EXW LW LV OLNHO\ WKDW WKH David Chapman of Ancient Arts ZDWHUZDVQRWYHU\FOHDQ%HHUPDNLQJKDVEHHQ reconstructing how beer might have been a recent suggestion and this has been tested by made in a burnt mound trough experimental archaeologists. &RS\ULJKW*Z\QHGG$UFKDHRORJLFDO7UXVW 05 Wales & West Utilities Pwllheli to Blaenau Ffestiniog Gas Pipeline A column of peat was taken from a marsh next to the large burnt mound at Pentrefelin. Pollen JUDLQVDUHSUHVHUYHGLQSHDWDQGFDQVKRZZKDWWKHYHJHWDWLRQZ WKHVSHFLHVIRXQGLQGLIIHUHQWOD\HUVRIWKHSHDWLWLVSRVVLEO RYHUWLPH7KHSROOHQJUDLQVRIHDFKVSHFLHVDUHFRXQWHGDQGSU EHORZ Pollen diagram from Pentrefelin Pwllheli M3 (%TLP-A lnus) Pollen Analysis 0 Betul a 5 2140 ± 30 10 15 Alnu s glutinosa 20 25 Trees Shrubs Dwarf shrubs Herbs Spores Indet. Aquatics 30 3020 ± 30 Que rcus 35 Depth40 (cm) Pinaceae Sorbus-type 45 Ulmus 50 Carpinus 55 Ilex Acer campe stre 60 Corylus avellana-type 65 70 Sambucus nigra 20 40 Hedera Bryonica dioi c a Lonicera being7KHHDUOLHVWSDUWRIWKHUHFRUGSUREDEO\GDWHGWRWKHODWH1HRO used and this showed100 200 a largely wooded landscape, withSalix alder carr woodland along the Erica-undiff Calluna DGMDFHQWVWUHDPDQGDPL[HGGHFLGXRXVZRRGODQGJURZLQJRYHUWK20 40 Cereal-type HWRVHHKRZWKHYHJHWDWLRQFKDQJHG Avena-Tr iticum -type Total ce real-type DVOLNHLQWKHSDVW%\VWXG\LQJ PLOOHQQLXPWKHUHZHUHRFFDVLRQDOHSLVRGHVRIZRRGODQGFOHDUDQFH Poaceae ODUJHVRPHZHUHIRU¿HOGVZKHUHFHUHDOVZHUHJURZQDQGVRPHZH Cyperaceae Rumex undiff. grew back after each of these short episodes. 204060 Plantago un d i ff. Ranunculus -typ e HVHQWHG LQ D SROOHQ GLDJUDP Rosaceae- undi ff Alc he milla-type Filipendula %\WKH,URQ$JHWKHZRRGODQGFOHDUDQFHEHFDPHPRUHH[WHQVLYHDQ Poten tilla-type ZHUHEHLQJJURZQLQ¿HOGVLQWKHDUHD)URPWKLVWLPHWKHODQGV Hype r ic u m perforat um-type Hypericum elodes type Lactuceae undiff DQGDUDEOH¿HOGVUDWKHUWKDQZRRGODQGDQGWKHSUHVHQFHRIKHDWK Artemisia-type Cirsi um-t ype Solidago-vi ga u rea - type was also expanding. Achill ea-type Apiaceae-undiff 2040 Rubiaceae- u n diff Stellaria holostea 2040 Caryophyll ac eqae undiff. 7KHXSSHUPRVWSDUWRIWKHSROOHQGLDJUDPVKRZHGIXUWKHUH[SDQVL Sinapsis until woodland was only present in isolated stands, hedgerows and along streams, and the Urtica dioca Vicia type Vicia cracca landscape was much as it is today. Some pine pollen represents the introduction of foreign trees Campanula-type Chenopodiaceae undiff Calystegia in plantations from the 18th century onwards. Anchusa arvensis Scutel laria Stachys sy l vatica type Symphytum Others Pteridium Pteropsida (monolete) indet. Polypod ium Pteropsi da (trilete) indet. Sphagnum Conceal e d/ Cr u m pled Degraded Total Indeterminate Myriophyllum-und iff Equisitum Potamogeton Sparginium Typha latifolia Charcoal Tr ee s Shrubs Dwarf s hrubs LWKLFZKHQWKHEXUQWPRXQGZDV Herbs 20 40 20 Zone M3 -vi HZLGHUDUHD2YHUWKHQH[W M3 -v 7KHVHFOHDUDQFHVZHUHQRW M3 -i v 06 20 UHIRUSDVWXUH7KHZRRGODQG M3 -i i i &RS\ULJKW*Z\QHGG$UFKDHRORJLFDO7UXVW 20406080100 FDSHZDVGRPLQDWHGE\JUDVVODQG M3 -i i M3 -i HUSROOHQVKRZVWKDWPRRUODQGGSHUPDQHQWDQGFHUHDOV RQRIJUDVVODQGDQGKHDWK Pollen grains seen under the microscope (from the left: lime, alder, hazel, grass) (Department of Geography, Royal Holloway College) Wales & West Utilities Pwllheli to Blaenau Ffestiniog Gas Pipeline BURQ]H$JH&UHPDWLRQ%XULDO 7ZRVPDOOSLWVZHUHLGHQWL¿HGLQD¿HOGVRXWKRI/ODQ\VWXPGZ\7KHVHFRQWDLQHGIUDJPHQWVRI