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Mountainous terrains are dynamic landscapes shaped by tectonic and climatic forces. For researchers seeking to understand the geologic history of these regions, studying the longitudinal profile of mountain rivers—essentially a graph plotting river elevation against distance along the stream—has long been an important investigative tool.  

Traditionally, abrupt changes in river slope were attributed to external factors such as tectonic shifts or climatic disruptions. However, new research provides evidence for another factor in this geological narrative: waterfalls forming spontaneously, due to feedback mechanisms within the river itself. 

The research team developed a comprehensive model to investigate the impact of waterfalls on river profiles. The study aimed to determine whether these self-formed water features could cause alterations in the absence of external factors like tectonic or climatic changes. 

"The research, led by Sophie D. Rothman at UNR, challenges the conventional understanding of river-profile evolution,” said Dr. Helen Dow, a USGS Mendenhall Postdoctoral Fellow and a co-author of the study. “Waterfalls, driven by feedback loops involving water flow, sediment transport, and river-bed erosion, can exert a profound influence on the shape of mountain rivers.” 

The team's model developed river profiles using the assumption that waterfalls naturally develop and alter erosion rates in channels that surpass a specific slope threshold. The results revealed distinct river-profile features that mirrored observations in waterfall-rich rivers in the southern Sierra Nevada mountains of California.  

This suggests that self-formed waterfalls can, in fact, generate longitudinal profile signatures that mimic those traditionally associated with external disruptions. 

The findings raise intriguing questions about the factors influencing mountain river profiles and offer a new perspective on the ongoing debate regarding the relative impacts of tectonics, climate, and internal feedback mechanisms on these rivers. By identifying similarities and differences in the effects of these influences, the study contributes to a more nuanced understanding of mountain river evolution.