Global InformationAllamoore Formation information
| Allamoore Formation | |
|---|---|
| Stratigraphic range: | |
| Type | Formation |
| Underlies | Tumbledown Formation |
| Overlies | Carrizo Formation |
| Thickness | 3,000 feet (910 m) |
| Lithology | |
| Primary | Limestone |
| Other | Chert, metavolcanic rock |
| Location | |
| Coordinates | 31°04′41″N 105°00′14″W / 31.078°N 105.004°W |
| Region | West Texas |
| Country |  United States |
| Type section | |
| Named for | Allamoore, Texas |
| Named by | P.B. King |
| Year defined | 1940 |
  Allamoore Formation (the United States)  Allamoore Formation (Texas) | |
The Allamoore Formation is a Precambrian geologic formation found in the vicinity of Van Horn, Texas. The formation is notable for the well-preserved microfossils found in chert beds within the formation. These may include early eukaryotes. Possible fossil burrows were reported in the formation in 1995, which would push the origin of the first animals (Metazoa) back to before 1000 million years ago. However, these have since been explained as diagenetic structures, formed by nonbiological processes as the sediments making up the formation were compacted and lithified.