claim: Large parts of North America was periodically covered by Cordilleran Ice Sheet.
evidence: Dundrod Circuit is a motorsport street circuit used for the RAC Tourist Trophy for sports cars between 1950 and 1955 and for the motorcycle Ulster Grand Prix from 1953 onwards .. RAC Tourist Trophy. RAC Tourist Trophy. Ulster Grand Prix. Ulster Grand Prix. motorsport. motorsport. street circuit. street circuit. sports cars. Sports car racing. It is situated in County Antrim , Northern Ireland .. County Antrim. County Antrim. Northern Ireland. Northern Ireland. The nearby Clady Circuit also in County Antrim was used for the Ulster Grand Prix between -LRB- 1922 -- 1952 -RRB- before moving to the Dundrod Circuit .. County Antrim. County Antrim. Ulster Grand Prix. Ulster Grand Prix. Clady Circuit. Clady Circuit