# chondrichthyesweek fossilfriday ironstone sandstone naturejournaling lagerstatteoftheweek fossils

They are fairly common on timberlands south of Olympia in the Lincoln Creek Formation. Been a long time since I've been there, but the logging roads were usually open to the public. Found this concretion in a fresh roadcut. Hope you have some luck!

2 11
2023-03-05

Bandringa was an ancient shark-relative found in the Mazon Creek concretions. The dominance of youngsters and egg cases suggest the area served as a nursery. What's more, arthropod remains are found in their stomachs.
https://t.co/OSHj0OEoF4

17 64
2022-04-29

Natural sandblasting has hollowed out the softer sandstone and left the resistant bands of ironstone standing to give a Swiss cheese effect to this block in an old sandstone wall.

https://t.co/AtKYcV5cTg

0 3
2021-05-10

Juveniles of the ancient shark-relative, Bandringa, are found in the Mazon Creek concretions. The lack of adults and dominance of youngsters and egg cases suggest the area served as a nursery.
https://t.co/nBCnjya325

9 43
2021-04-04

Ichthyosaur bones can create patterns of ridges in the shale, even if bones can’t be seen. Other fossils & mineral concretions can form bumps too. Pic shows the bones in section - half an ichthyosaur bone looks like a black bow tie. 6/9

0 1
2020-11-19

Ichthyosaur bones can create patterns of ridges in the shale, even if bones can’t be seen. Other fossils & mineral concretions can form bumps too. Pic shows the bones in section - half an ichthyosaur bone looks like a black bow tie. 6/9

3 11
2020-05-03

A rock that is sedimentary but doesn't look or feel sedimentary! Siderite concretion for Inktober :)

0 2
2019-10-24