ilmen clint

geology clint novgorod sedimentary rocks frasnian stage upper devonian flaglike limestones shelly facies gastropods brachiopods fossils limestone ammonoid aqueous rock bold coast buhr stone buhrstone building bur burr calcareous cam carbonate lime cement chalk cliff cliffy shore collection crushed extinct organisms fossil freestone geological record indurated layers layer metamorphosed natural stones ooze paleontology rag lake scar scarp beach steep bank wall