If fire spall dominates the weathering and erosion of boulder surfaces on Sierran glacial moraines, and fire spalls are typically 1 cm thick, calculate the effect of fire spall on the CRN-based age of a boulder. Assume the true age of the surface is an LGM one, about 18 ka, and recurrence interval of fire spall is

i) 1000 years,

ii) 200 years. First, think about the problem and discuss what direction this effect would move the age (younger or older than the true age).