Portland Group (geology)
（重定向自Portlandian）
![](/Images/godic/202502/03/Cliffs,_west_side_of_Portland_-_geograph.org.uk_-_13165720530.jpg")
- For the computer company, see The Portland Group
The Portland Group (or Portlandian) is an Upper Jurassic lithostratigraphic group (a sequence of rock strata) in south-east England. The name is derived from the Isle of Portland in Dorset where the strata are exposed and have been extensively worked.