Several studies of sediment (e.g., dirt, pieces of rock, etc.) in streams have shown an inverse correlation between sediment grain size and downstream distance from the primary sediment source, suggesting that stream length has a sorting effect on sediment. In a study of sediment sampled at more than a dozen sites in Alpine streams, however, geologists Camille Litty and Fritz Schlunegger found that cross-site variations in grain size were not associated with differences in downstream distance, though they did not conclude that downstream distance is irrelevant to grain size. Rather, they concluded that sediment influx in these streams may have been sufficiently spatially diffuse to prevent the typical sorting effect from being observed.

Question

Several studies of sediment (e.g., dirt, pieces of rock, etc.) in streams have shown an inverse correlation between sediment grain size and downstream distance from the primary sediment source, suggesting that stream length has a sorting effect on sediment. In a study of sediment sampled at more than a dozen sites in Alpine streams, however, geologists Camille Litty and Fritz Schlunegger found that cross-site variations in grain size were not associated with differences in downstream distance, though they did not conclude that downstream distance is irrelevant to grain size. Rather, they concluded that sediment influx in these streams may have been sufficiently spatially diffuse to prevent the typical sorting effect from being observed.

Which finding about the streams in the study, if true, would most directly support Litty and Schlunegger’s conclusion?
Choose 1 answer:
Choose 1 answer:
(Choice A) The streams contain several types of sediment that are not typically found in streams where the sorting effect has been demonstrated.
A
The streams contain several types of sediment that are not typically found in streams where the sorting effect has been demonstrated.
(Choice B) The streams are fed by multiple tributaries that carry significant volumes of sediment and that enter the streams downstream of the sampling sites.
B
The streams are fed by multiple tributaries that carry significant volumes of sediment and that enter the streams downstream of the sampling sites.
(Choice C) The streams mostly originate from the same source, but their lengths vary considerably due to the different courses they take.
C
The streams mostly originate from the same source, but their lengths vary considerably due to the different courses they take.
(Choice D) The streams regularly experience portions of their banks collapsing into the water at multiple points upstream of the sampling sites.
D
The streams regularly experience portions of their banks collapsing into the water at multiple points upstream of the sampling sites.

Answer 1

(Choice B) The streams are fed by multiple tributaries that carry significant volumes of sediment and that enter the streams downstream of the sampling sites.