Blyth travelled to Whitley Bay on a bitterly cold afternoon and suffered their second defeat in a row against a strong and fit Rockcliff side.
Missing five first team regulars, Blyth struggled to cope with the power of the Rockcliffe forwards.
The home side forced an error from Blyth, giving them the first three points before the visitors were further disrupted in the pack, losing first their prop then second row to injury.
The home forwards were in control and scored two tries from driving mauls before half-time, giving them a 13-point advantage.
Blyth's injury jinx struck again when centre Bradwell left the field with a shoulder injury.
The Rock forwards again caused havoc in the Blyth defence and scored again to stretch the lead to 18-0.
Blyth then enjoyed their best spell of the game, Liam Allen out-pacing the defence for a try before a catch and drive lineout gave them the second try.
The visitors thought they were back in the game but a further penalty and another score by the home forwards put the game beyond them.
Next week's game is against Ponteland in the semi-final of the cup.
Blyth have given up home advantage having been offered the use of the new all-weather pitch at the Newcastle Falcons ground. Kick-off should be 2pm but supporters are asked to check with the club before travelling.