Daw'r darluniau ar y tudalennau canlynol o'r gyfrol 'The Vale of Nantgwilt - A Submerged Valley' (1894) gan Richard Eustace Tickell. Roedd Tickell yn beiriannydd sifil ac ef oedd yn gyfrifol am arolygu'r gwaith o godi argae Pen-y-garreg, a oedd yn rhan o gynllun gwaith dŵr Cwm Elan 1892. Yn ei gyflwyniad i'r llyfr, esboniodd Tickell pam yr aeth ati i lunio'r gyfrol:

'The object of this book is to commemorate scenes in one of the most charming valleys in Great Britain. Scenes which are soon to be lost for ever, submerged beneath the waters of a series of lakes, which, by a colossal engineering undertaking, are about to be constructed for the purpose of supplying water to the city of Birmingham, nearly eighty miles away.

The Vale of Nantgwilt lies at the junction of the rivers Elan and Claerwen on the borders of Radnor and Brecon, to the west of the Wye, into which the Elan falls near the little market town of Rhayader. In this neighbourhood upwards of 45,000 acres of land have been acquired by the Corporation of Birmingham under Act of Parliament ...'