Differential intensity, j(T, z), of solar cosmic rays (red lines) and Galactic cosmic rays (grey lines) in the early Earth atmosphere for Ω = 6Ω_⊙, plotted at different heights above and at the surface as a function of T. The linestyles represent these heights (solid: top of atmosphere (TOA); dotted: 1000 km; dashed: 500 km; dot-dashed: surface). Here the surface is defined as z = 0.001 km.