Marbled sandstone?

[aadenny]

Today I came across a sandstone hill which has been cut to make a road, and the cross-section of sandstone has occasional hard white layers typically an inch or two thick, looking a bit like marble, spread throughout the hill, and at all sorts of angles. I was wondering how these layers of what is a completely different substance came to be in the sandstone. I realise this is probably a basic GCSE geology question, and I'm about 3 times the age of the average schoolboy and never did geology at school, sorry!

[marronman]

Could be salt if it was a desert sandstone. Could also be other white coloured minerals which have percolated through the sandstone at a later date. Additionally, it could be a metamorphic rock which was originally a sandstone with limey bands/beds. These lime beds will be a form of marble.This metamorphic action could also pass minerals through the sandy beds under pressure. Sorry if I've confused you further. Would need to see it to tell you better.