Within lower Eskdale, Yorkshire, England, and its tributary valleys three thin series of Dogger (Jurassic) deposits, all marine but largely unfossiliferous, may be recognized superimposed upon each other. The sideritic sandstone of the Whitby basin is the oldest and is contemporaneous with the Glaisdale oolite to the west, a low-grade fine-grained sandy oolitic ironstone laid down in a more restricted marine lagoon. Later in an eroded area near Grosmont the Chamositic facies was deposited. The third and final phase of deposition is seen in the Ajalon facies of southwest Glaisdale and Hollins Wood, Beckhole, coarse-grained, low-grade ironstones, massive, very sandy and pebbly chamosite-oolites with a siderite matrix, occurring as lenticular or boat- shaped deposits which in Glaisdale cut into but not through the Glaisdale oolite.