According to Widipedia: "Treacle is any syrup made during the refining of sugar cane and is defined as "uncrystallized syrup produced in refining sugar". Treacle is used chiefly in cooking as a form of sweetener or condiment.
The most common forms of treacle are the pale syrup that is also known as golden syrup and the darker syrup that is usually referred to as dark treacle or black treacle. Dark treacle has a distinctively strong flavour, slightly bitter, and a richer colour than golden syrup, yet not as dark as molasses.