v.

become steeper

"The mountain side has steepened"

make steeper

"The landslides have steepened the mountain sides"

Steepening of Afterglow Decay for Jets Interacting with Stratified Media
the supercontinuum laser source || self-steepening of optical pulses
Steepening of kinetic magnetosonic waves into shocklets: Simulations and consequences for planetary shocks and comets
Visible Harmonic Emission as a Way of Measuring Profile Steepening
Self-Modulation, Self-Steepening, and Spectral Development of Light in Small-Scale Trapped Filaments
Role of the anomalous self-steepening effect in modulation instability in negative-index material
Vector analysis of astigmatism changes by flattening, steepening, and torque.
Quaternary deformation, river steepening, and heavy precipitation at the front of the Higher Himalayan ranges
Nonlinear asymmetric self-phase modulation and self-steepening of pulses in long optical waveguides
Magma generation by slab steepening and breakoff beneath a subduction‐accretion complex: An alternative model for collision‐relate...