| Chamberlain's Brook Formation | |
| Type: | Formation |
| Age: | Middle Cambrian ~ |
| Period: | Cambrian |
| Prilithology: | Green, purple and red siliciclastic marine mudstones[1] |
| Region: | Atlantic coast |
| Country: | |
| Unitof: | Adeyton Group[2] |
| Subunits: | Fossil Brook Member (and others) |
| Underlies: | Manuels River Formation (unconformably?) |
| Thickness: | up to 14m (46feet) |
| Map: | Chamberlains Brook Formation map.svg |
The Chamberlain's Brook Formation is a thin but distinctive geologic formation of dark red calcareous mudstones[3] that crops out from Rhode Island to Massachusetts and, Nova Scotia, New Brunswick and Newfoundland.[1] It preserves fossils, including trilobites, dating back to the lower mid-Cambrian period.[1] Its lowermost member is the Braintree Member (lowest Middle Cambrian) and the uppermost member is the Fossil Brook Member.[1]