described at URL: https://www.flickr.com/photos/royluck/5204321634/ operator: Flickr URL: https://live.staticflickr.com/5084/5204321634_e8cd0bfa1a_o.jpg...
flickr.com/photos/royluck/5203527666/ operator: Flickr URL: https://live.staticflickr.com/4090/5203527666_bb58976e4a_o.jpg determination method: SHA-1...
California. Cross-section through a sample of the Old Red Sandstone showing quartz and chert pebbles; central England; scale bar is 10 mm. Bedding plane of...
