The Roman Map of Britain Edrotalia Melandra Castle, Glossop, Derbyshire
Zerdotalia (R&C 108) next
The river Etherow seems a likely candidate as the first part of the name with W tal 'brow, edge, end' as the second. Etherow is recorded Ederou 1285, Edderowe 1290. The -erdo- looks like a scribal metathesis of edro. The Z is either a contaminant from the previous entry Aquis Arnemeza, or the result of a misinterpreted text divider . There is no problem is reconstructing an Edrotalia 'Ethererow brow'. ERN etherow 156 compares it with the Scottish Adder Edre ca. 1050. Nicolaisen does not mention the Etherow when considering the river name Adder. CDEPN has this as 'Originally a hill name... OE ędre 'water-course'.
R&C's widely accepted approach is to emend Zerdotalia to Ardotalia 'high brow'.
Melandra Castle SK0095
Margary 714 connects Buxton, the previous entry, to Melandra Castle. This is noted in the Addenda to Margary's 3rd edition p520 and is not portrayed his map or the 5th ed OS Map of Roman Britain.