Do clothing/synthetics decompose in silt?

Organic materials decompose first. That would include clothing made of cotton, wool, lined, silk. The soft tissue of the body decomposes first. Bones would remain We have found bones in bogs that are thousands of years old. Iron rusts, not metal. Metal will tarnish. In some cases the tarnish covers the metals and stops further deterioration. Salt causes corrosion, rust is a type of corrosion. It tends to accelerate rusting of iron. Sometimes sediments bury things and actually protect them from destruction. Dinosaur bones have been found in layers of sediment. Metals would probably remain. Plastics would tend to remain. Very few are biodegradable. Synthetic fibers such as nylon, polyester, biodegrade extremely slowly. I just finished a book regarding bog people findings, the chemicals in the bog actually tanned the skin and the bodies recovered were shrunken and browned.