492 



THE WONDERS OF GEOLOGY. 



Lect. V. 



THE OOLITIC OR JURASSIC SYSTEM. 



Upper oolite 

 of the Isle of 



Portland, Wilts, ( 

 Bucks, Berks, 



Oxfordshire, &c 



Middle oolite. 



Lower oolite. 

 Gloucestershire, 



Oxfordshire, J 

 and Northamp- 

 tonshire. 



Lower oolite 



of the 



Yorkshire coast. 



oolite. 



1. Portland oolite ; — limestone of an oolitic struc- 



ture, abounding in ammonites, trigoniae, &c, 

 and other marine exuviae ; green and ferrugi- 

 nous sands ; layers of chert ; drifted wood, 

 cycadeous plants ; bones of turtles and lizards. 



2. Kimmeridge clay ; — blue clay, with septaria and 



bands of sandy concretions ; marine reptiles, 

 fishes, shells, corals, and other organic remains. 



1. Coral oolite, or coral-rag ; — limestone composed 

 of corals, with shells and echini ; coral reefs. 



2. Oxford clay; with septaria ; abounding in fossils ; 



beds of calcareous grit, called Kello way-rock ; 

 also full of shells, corals, and other organic 

 remains. 



1. Cornbrash; — a coarse shelly limestone. 



2. Forest marble; — layers of fissile arenaceous 



limestone — coarse shelly oolite— sand, grit, and 

 blue clay. 



3. Great oolite — calcareous oolitic limestone and 

 freestone ; upper beds, aggregates of shells. 

 Stonesfield slate ; containing leaves and fruits 

 of palms, cycadeas, and other land plants ; 

 insects, reptiles, and mammalia. 



4. Fuller's earth beds; — marls and clays, with 



fuller's earth— sandy limestones with shells. 



5. Cheltenham or Inferior oolite; — coarse lime- 

 stone — conglomerated masses of terebratulae 

 and other shells — ferruginous sand, and con- 

 cretionary blocks of sandy limestone, and shells. 



1. Cornbrash; a thin bed of rubbly limestone; 

 which in many parts is a mere aggregation of 

 shells and other fossils. 



2. Sandstones and clays, with land plants; thin 



coal and shale' ; calcareous sandstone and shelly 

 limestone. 



3. Sandstone, often carbonaceous, with clays, full 



of leaves of terrestrial plants ; beds of coal and 

 ironstone. 



4. Limestone, ferruginous and concretionary sands. 



