Cealca ceaster

According to the Old English Dictionary:

Cealca ceaster

gen. ceastre; f. The chalk city. Camden thinks it is Tadcaster, in Yorkshire; idem, ut opinatur clarus Camdenus, quod hodie Tadcaster in agro Eboracensi, sic olim vocatum a ealce ibidem copiose effossa, Som. Ben. Lye. cealca ceaster