Ageologist is working in an area of old volcanic rocks exposed by erosion. he finds a large rock outcrop that contains flat lying gravels in the base of the outcrop. these gravels are over-lain by basalt that forms a series of layers representing flows. the uppermost basalt lava flows have a dip of about 10 degrees to the west. what does this outcrop record? a) basalt flows formed above a series of gravels, filling a river valley. b) basalt flows formed after gravels were deposited, covered the local terrain, and built a shield volcano with dips of about 10 degrees. c) gravels were initially deposited in a river valley and a cinder cone was erupted, damming the valley, before a cinder cone formed. d) you can't tell anything about the history of this region from this outcrop.