  Subsequent to the Moon's formation, late accretion to the terrestrial planets
modified their silicate crusts and mantles. We combine dynamical N-body and
Monte Carlo simulations to determine impact probabilities, impact velocities,
and expected mass augmentation onto the terrestrial planets from three sources:
planetesimals left over from primary accretion, asteroids from the E-belt, and
comets arriving from the outer Solar System. We present estimates of the amount
of cometary material striking the terrestrial planets in an early episode of
planetesimal-driven giant planet migration (Mojzsis et al., 2019). The Moon and
Mars suffer proportionally higher cometary accretion than Venus and Earth. The
background mass addition from small leftover planetesimals to Earth and Mars is
far less than independent estimates based on their mantle abundances of
highly-siderophile elements. This supports the theory that both planets were
struck by single large bodies that delivered most of their mass augmentation
since primary accretion. We present fits to the impact chronologies valid from
4500 Ma to ca. 3700 Ma. The lunar timeline thus obtained is at odds with both
the calibrated Neukum (Neukum et al., 2001) and Werner (Werner et al., 2014;
Werner, 2019) chronologies. For Mars, the match with its calibrated Werner
chronology is no better; by increasing the mass of the E-belt by a factor of
four the dynamical lunar and martian chronologies are in line with that of
Werner (2019) and match constraints from the current population of Hungaria
asteroids. Yet, neither of our dynamical timelines fit well with that of
Neukum. The dynamical lunar and martian chronologies are also different from
each other. Consequently, the usual extrapolation of such chronologies from one
planetary body to the other is technically inappropriate.
