The Yale Undergraduate Research Journal


Gravitational interactions among masses in the solar system are recorded in Earth’s paleoclimate history because variations in the geometry of Earth’s orbit and axial orientation modulate insolation. However, astronomical models are unreliable before ~50 Ma due to the chaotic nature of the solar system and therefore must be constrained using geological observations. Here, we use environmental proxies from paleo-tropical Late Triassic lake deposits of the Newark Rift Basin to identify and tune to previously undescribed strong variations in orbital inclination. Tuning to the 173 kyr Earth-Saturn inclination cycle, theoretically stable due to the high mass of Saturn, reveals both other predicted inclination cycles and previously reported eccentricity cycles. Slight, complementary offsets in the eccentricity and inclination cycles shown by the Earth-Saturn (s3-s6) and Venus-Jupiter (g2-g5) tunings may be due to chaotic variations of the secular fundamental frequencies in Earth’s nodal and Venus’s perihelion orbital precessions. The strength of the inclination cycles suggests that the Earth system modulates orbital pacing of climate and provides a mechanism to further constrain astronomical solutions for solar system dynamics beyond the ~50 Ma limit of predictability