250 Mr. Lonsdale on the Oolitic District of Bath. 



1. Blue and yellow clay, with nodules of indurated marl. ... 30 to 40 feet. 



2. Bad fuller's earth 3 to 5 feet. 



3. Good fuller's earth 2^ to 3 feet, 



4. Clay containing beds of bad fuller's earth and layers of 



nodular limestone, and indurated marl 100 feet. 



1. The clay or marl which constitutes the upper part of the series is 

 generally of a tough nature, and effervesces with an acid. Masses of that 

 variety of calcareous spar called "cone in cone" are frequently found in it. 



2. The bad fuller's earth is of a sandy nature^ effervesces strongly ;, and 

 in general contains numerous fragments of shells. 



3. The good fuller's earth is of two kinds, one blue, the other brown. 

 They are irregularly associated, and the latter variety is considered to be of 

 superior quality to the former. 



4. The lower clay incloses one or two strata of a tough, rubbly limestone, 

 which is commonly called the "fuller's earth rock." This stone is for the 

 greater part of a very close texture, and bears so considerable a resemblance 

 to cornbrash that it might be mistaken for that formation. The fossils, how- 

 ever, which peculiarly belong to each, afford an almost unerring distinction. 

 The fuller's earth rock is always accompanied by an immense number of 

 Terebratulffi ; and Mija angulifcra and Jsocardia concentrica are almost 

 invariably found in it. These organic bodies are wanting in the cornbrash, 

 which is characterized by the constant presence of Avicula cchinata, a shell 

 of very rare occurrence in the older formation. The nodules of indurated 

 marl, which also accompany the lower clay, sometimes agree in colour and 

 texture with blue lias. 



The fuller's earth formation describes a zone around the sides of the 

 hills from Tog Hill near Wick, to Green Parlour near Radstock, and occupies 

 the same geological position, between the inferior and great oolites, from the 

 first of those localities to Hinton Field Farm, about one mile from Charter 

 House Hinton ; but the great oolite thins out at that point, and for the 

 remainder of the district it is interposed betwixt the inferior oolite and the 

 forest marble. 



The good fuller's earth is confined to the brow of Odd Down and the side 

 of Midford Hill. 



Great Oolite. 



A thorough acquaintance with this important formation illustrates the 

 influence which organic remains have on the external characters of a rock, 

 and prepares the inquirer for examining with greater facility the superior 

 oolitic deposits. When the great oolite is almost entirely free from fossils. 



