The entrance road to Henry Cowell Redwoods State Park crosses the San Lorenzo River and winds through a broad flat meadow. To Noah Finnegan, a geomorphologist who studies rivers, something about this landscape doesn’t look quite right. … [A]t some point in the past, the San Lorenzo River cut down into its channel and abandoned the floodplain. So they set out to determine when that happened and why. Their findings, published in December in the journal Earth Surface Processes and Landforms, connect this dramatic change in the river’s behavior to logging practices in the Santa Cruz Mountains in the 1800s.