Fig. 3

a Amber, plant fossil and glauconite pocket within shale indicated by yellow, blue and green arrows, respectively. b Granular amber within black shale. c Pyroclastics of unit 1. d Grey shale with amber (yellow arrow) and plant fossils (blue arrow) in unit 2. e Black shale with amber (yellow arrow) and plant fossils (blue arrow) in unit 2. f Grey shale with glauconite pocket (green oval) in unit 2. g Grey shale with pyrite (yellow oval) and plant matter (blue arrow) in unit 2. h Green shale in unit 3, glauconite indicated by green arrow; white dots are fragments of fossil molluscs. i Grey shale with pockets of glauconite and mollusc fragments in unit 3. j Green shale with pyrite (yellow arrow) in unit 3. k Shell limestone with mollusc fossils in unit 3; yellow and green arrows indicate Caestocorbula sp. and Claibornicardia sp., respectively. l Mollusc concentration in upper part of unit 3. m Black shale with plant fossil (blue arrow) in unit 4. n Lignite in unit 4. o Ferricrete in unit 4. Scale bars 10 mm