Coitur toerth (Field).
Grid Reference: SJ 08773 81030. Parish: Gwaenysgor, Flintshire
When recorded: 1841. Primary Source: none. Secondary Source: Cynefin

Colloery (Unclassified).
Grid Reference: ST 11649 96984. Parish: Gelligaer, Glamorgan
When recorded: 1898-1908. Primary Source: OS 2nd Edition Maps. Secondary Source: GB1900 website

Craig Cwm-oergwm (Unclassified).
Grid Reference: SO 03636 20197. Parish: Llanfrynach, Brecknockshire
When recorded: 1898-1908. Primary Source: OS 2nd Edition Maps. Secondary Source: GB1900 website

CWM FFRWD OER BRANCH (Unclassified).
Grid Reference: SO 25896 01109. Parish: Abersychan, Monmouthshire
When recorded: 1898-1908. Primary Source: OS 2nd Edition Maps. Secondary Source: GB1900 website

Cwm Ffrwd-oer Farm (Unclassified).
Grid Reference: SO 25860 01277. Parish: Abersychan, Monmouthshire
When recorded: 1898-1908. Primary Source: OS 2nd Edition Maps. Secondary Source: GB1900 website

Cwm Lloer (Unclassified).
Grid Reference: SH 66380 62097. Parish: Capel Curig, Caernarfonshire
When recorded: 1898-1908. Primary Source: OS 2nd Edition Maps. Secondary Source: GB1900 website

Cwm oer nant (Field).
Grid Reference: SN 41758 21434. Parish: Carmarthen St Peter, Carmarthenshire
When recorded: 1841. Primary Source: none. Secondary Source: Cynefin

Cwm Oerddwr (Unclassified).
Grid Reference: SH 57806 44896. Parish: Beddgelert, Caernarfonshire
When recorded: 1898-1908. Primary Source: OS 2nd Edition Maps. Secondary Source: GB1900 website

Cwm Oergwm (Unclassified).
Grid Reference: SO 04593 21150. Parish: Llanfrynach, Brecknockshire
When recorded: 1898-1908. Primary Source: OS 2nd Edition Maps. Secondary Source: GB1900 website

Cwm-coed-oeron (Unclassified).
Grid Reference: SN 83879 38883. Parish: Llanfair-ar-y-bryn, Carmarthenshire
When recorded: 1898-1908. Primary Source: OS 2nd Edition Maps. Secondary Source: GB1900 website