In 1977, J. A. Westgate of the University of Toronto suggested that a smaller eruption may have occurred at the Bridge River Vent after the eruption 2,350 years ago, sending tephra to the southeast. A tephra deposit overlying the Bridge River Ash at Otter Creek shows strong genetic relationships with the Bridge River Ash, differing only by its absence of biotite. In earlier publications, this tephra is classified as part of the Bridge River Ash. However, it has been dated to be about 2,000 radiocarbon years old, indicating that this tephra is a few hundred years younger than the Bridge River Ash. Apparent absence of biotite and occurrence well to the south of the Bridge River Ash likewise favour a separate identity.