Owen's chief literary work was the ‘Description of Pembrokeshire,’ dated 18 May 1603, which was indifferently edited, with some important omissions, for the ‘Cambrian Register’ (vols. i. and ii.) in 1795–6 by Richard Fenton. The copy used by Fenton subsequently belonged to Sir Thomas Phillipps [q. v.] (Phillipps MS. 13474). The original manuscript in the British Museum (Harleian MS. 6250) has been faithfully reproduced by a descendant of the author, Mr. Henry Owen of Withybush, under the title of Owen's ‘Pembrokeshire’ (Cymmrodorion Record Ser., No. 1, London, 1892, 8vo). Another autograph manuscript has since been discovered in the Marquis of Bute's collection (Arch. Cambr. 5th ser. ix. 330); and a transcript of Harleian MS. 6250, made by Bishop Burgess, is now in the library of St. David's College, Lampeter. In design the work is similar to Carew's ‘Survey of Cornwall,’ and presents a valuable picture of country life in the Elizabethan age. But it also contains so remarkably accurate an account of the geology of South Wales that Owen has been styled ‘the patriarch of English geologists’ (see Edinburgh Review, April 1841, lxxiii. 3; cf. Conybeare, Outlines of Geology, ed. Phillips, 1822, Introduction, p. xl).
Among Owen's other works are the following: 1. ‘The Description of Wales,’ written in 1602, and printed in the ‘Gentleman's Magazine’ (1823, pt. ii.) from an inaccurate transcript (Phillipps MS. 6359) of the original autograph manuscript now preserved at the Bodleian Library (Gough MS. Wales, No. 3; see its history in Gough, British Topography, 2nd ed. 1780, ii. 495). [See Harry, George Owen, to whom it is ascribed in error.] 2. ‘The Description of Milford Havon,’ written in 1595, probably with the view of inducing the government to fortify the haven. There is an autograph copy in the Phillipps Library, MS. 14445 (see Penruddock Wyndham, Tour through Wales, 1781 edit. p. 70), and a transcript among the Additional MSS. in the British Museum (No. 22623). 3. ‘A Cataloge and Genelogie of the Lordes of Kemes,’ being Rawlinson MS. B. 469 in the Bodleian. The foregoing three works are printed (from the originals) in the appendix to Owen's ‘Pembrokeshire.’ 4. ‘Baronia de Kemes,’ being a treatise on the position of Kemes as a lordship-marcher, together with charters and documents relating to the barony, collected by Owen, and preserved at Bronwydd, near Cardigan. These, with some other shorter tracts, were published by the Cambrian Archæological Association in 1861–2 (London, 8vo). Seven of the charters, with Owen's notes, had been previously published in 1841 by Sir Thomas Phillipps at the Middlehill Press under the title of ‘Cartæ Baroniæ de Kemes ex MSS. Georgii de Carewe arm. de Crowcombe in Com. Somerset.’ 5. ‘A Treatise of the Government of Wales,’ printed in Clive's ‘History of Ludlow’ (pp. 97–146) from Lansdowne MS. No. 215, art. 1, in the British Museum, which appears to be in part a copy of the Harleian MS. 141, art. 1, which is given in the appendix to Owen's ‘Pembrokeshire,’ and was previously printed incorrectly in Lloyd's ‘History of Powys Fadog,’ ii. 1. A summary of this tract is also given in Pennant's ‘Tours in Wales’ (ed. Rhys, iii. 265).
Besides the above, Owen left a considerable quantity of short treatises, many of which fell into the hands of Fenton, who at one time intended publishing them (see his Pembrokeshire, p. 403), but several of them were subsequently sold by his son in 1858 to Sir Thomas Phillipps. Among those not already enumerated are Owen's commonplace book, called ‘The Taylor's Cushion’ (Phillipps MS. 14427), which is referred to in Rees's ‘Beauties of England and Wales’ (vol. xviii. under ‘South Wales,’ sub fine), and a collection of Welsh pedigrees is attributed to him. Another volume of pedigrees, written mostly in Owen's hand, and in part printed in Lewis Dwnn's ‘Heraldic Visitations’ (ii. 293–364), where Owen is erroneously identified by the editor with his son, George Owen, York herald (cf. also i. 7, 8, and Introduction, p. xxvii, where an englyn by Dwnn in honour of Owen is printed), is preserved in the British Museum (Egerton MS. 2586), while Harleian MS. 6068 also contains some legal tracts by him. An extensive manuscript, known as the ‘Vairdre Book,’ containing inter alia a survey of the barony of Kemes, made in 1594, is preserved at Bronwydd. Another topographical work in Owen's hand, entitled ‘Pembrock and Kemes,’ came into the possession of Mr. Henry Owen of Withybush. A similar manuscript (now lost) is summarised in Browne Willis's ‘Survey of the Cathedral Church of St. Davids’ (pp. 38–73), London, 1717, 8vo, and is there assumed (cf. Gough, British Topography, ii. 515) to have been written by Owen for the use of Camden in preparing probably the sixth edition of the ‘Britannia’ (1607, fol.). To that work Owen also supplied a map of Pembrokeshire (pp. 508–9), a facsimile of which is prefixed to Owen's ‘Pembrokeshire’ (ed. 1892). Other short pieces by Owen have been printed in ‘Archæologia Cambrensis’ (3rd ser. viii. 14–