I am building an HO industrial switching layout (approx. 18 inches x 25 feet) in an eastern setting. My railroad is my own fictional name, but it interchanges with the B&O. Roadbed is flat cork sheets – no mainline ballast shape. Sidings and small yard are code 70. The rest is code 83. 1. I would appreciate advice on appropriate choices for code 83 and something a bit darker for coded 70 ballast. I would like to mix HO and N scale textures. 2. How much difference is there between dirty and regular industrial dirt? 3. Any suggestions for creek sand and rocks? Thanks for your help. — Ken Heinen