Why do Venusian mountains lack river and glacier erosion features?

Venusian mountain belts lack the river and glacier erosion features common on Earth primarily because the planet lacks liquid water and ice on its surface.1

On Earth, the flow of rivers and glaciers is a primary agent in wearing down mountain ranges over time. In contrast, the surface environment of Venus is characterized by extremely high temperatures—with surface readings reaching approximately 750 K (477 °C, or 891 °F)—which prevents the existence of liquid water or ice.21

Without these erosional forces, Venusian mountains retain steep slopes formed by tectonic processes such as folding and faulting. In some instances, these slopes have become so steep that they have collapsed under their own weight, creating a landscape that differs significantly from the eroded, weathered mountain ranges found on Earth.1