Forward propagation is used to compute the acoustic field in a shallow-water environment with a layered dipping sediment. The sediment is assumed to be silty with several thin sandy layers with higher density and sound speed. The sandy layers slope within the entire sediment layer so that the depth of a sand layer varies linearly with range. The sediment is modeled as a fluid of uniform horizontal thickness over a range-independent hard sub-bottom. The water sound speed is range independent and depth dependent in a fixed depth environment. This range-dependent sediment geometry leads to transmission loss significantly different from those with fixed layer depths, even when the dip gradient is very slight. These differences and their mechanisms are explored for varying frequencies and interlayer distances.