In an orogenic belt-foreland basin setting, sediments from the mountain are transported downstream and accumulate in foreland basins. Sediments routing through the network of rivers display downstream grain size fining due to sorting and abrasion (Paola et al., 1992). A grain size transition from gravel to sand, termed the gravel-sand transition (GST; Ferguson et al., 1996), occurs in a short downstream distance from the sediment source. The GST is preserved in the stratigraphy of a sedimentary basin as the conglomerate-sandstone transition (CST; e.g., Dubille & Lavé, 2015). The position of the CST in a foreland basin succession is determined by basin subsidence, sediment supply, and grain size (Allen et al., 2013; Armitage et al., 2011), and all these factors depend on the interactions of tectonics in the adjacent mountains and regional climate (Dingle et al., 2016, 2017; Duller et al., 2010; Quick et al., 2020). The propagation of the orogenic wedge toward to the foreland drives the forelandward migration of the coupled foreland basin system as well as sedimentary facies (Flemings & Jordan, 1989