| Calvert Formation | |
| Country: | United States |
| Overlies: | Old Church Formation |
| Underlies: | Choptank Formation |
| Unitof: | Chesapeake Group |
| Region: | Maryland, Virginia, Delaware |
| Namedfor: | Calvert County |
| Period: | Neogene |
| Type: | Formation |
The Calvert Formation is a geologic formation in Maryland, Virginia, and Delaware. It preserves fossils dating back to the early to middle Miocene epoch of the Neogene period, between 23 and 14 million years ago.[1] It is one of the three formations which make up the Calvert Cliffs, all of which are part of the Chesapeake Group.
The Calvert Formation is extremely fossiliferous, although the most fossiliferous layers constitute a relative small section of it, dating to about 16 to 14.5 million years ago. Sediments under these layers are composed of either fine sand with few shells or (for the earliest layers) diatomite. Some of the fossil species represented include the following:[2] [3]
| Edaphodon | E. sp | two well preserved mandibular plates | Similar to E. sweeti | |||||
| Ischyodus | I.sp | many tooth fragments occasional mandibular plates | ||||||
| Chimaera | C. sp | Cimaeridae |
| Notorynchus | N. primigenius | Hexanchidae | Similar to extant N. cepedianus but differs in distribution. | |||||
| Hexanchus | H. gigas | Hexanchidae | Far less common then N. primigenus | |||||
| Echinorhinus | E. blakei | Echinorhinidae | Teeth and bramble thorns | One of the rarest sharks in the cliffs, prefers deeper waters | ||||
| Squalus | S. sp. 1S. sp. 2 | Squalidae | Very rare | Two forms of teeth, one (S.sp 2) similar to Squalus acanthias | ||||
| Squatina | S.sp | Squatinidae | Teeth and Dermal thorns | |||||
| Rhincodon | R. typus | Rhincodonidae | Very similar to modern R. typus | |||||
| Carcharias | C. cuspidatusC. taurusC. reticulatus | |||||||
