AGES OF BURIED FORESTS. 179 



remains of ancient forests are not unknown in other lands. 

 In making the New Orleans and Denur railroad, from 20 

 to 35 miles from Davern, between Running Creek and 

 Cherry Creek, the workmen came upon a buried forest, 

 the trees of which had all of them become petrified. They 

 were of all sizes. They were found at different depths 

 ranging from 10 to 20 feet, the greatest depth to which 

 they had occasion to excavate. They were met with in 

 some half-dozen localities, and occasioned no little trouble 

 to the workmen. The trees were perfect, and could be 

 taken out almost unbroken if suitable appliances were 

 employed. 



Of buried trees in a fossil state we have numerous 

 specimens in what is known as the Purbeck Forests, in 

 the Isle of Portland. Of these forests, remarks a writer 

 in the Cornhill Magazine (vol. xlvi., p. 727), we get the 

 best remains in the so-called dirt-beds. These curious 

 layers consist of the actual surface of the ground in which 

 the trees grew, with the stumps and roots still standing 

 in their natural positions on that very ancient soil. Of 

 course, the wood itself is turned into stone ; but the form 

 and character of the tissues and leaves is still accurately 

 preserved for us. Some of the trees were cycads, a small 

 palm-like tropical species like the zamias of our own conser- 

 vatories ; others were pieces of extinct sorts, all requiring 

 a warmer climate than that of Britain at the present day. 

 They have fortunately been preserved for us in situ, as 

 they grew, by the fact that when the forests were gently 

 and gradually submerged beneath the waters of the lake, 

 the trees fell into the marshy bottom, and both trunks and 

 stumps, with the soil on which they had grown, were then 

 slowly covered up with a thin layer of lacustrine mud. 

 As a consequence; of these frequent changes, which are 

 much like those still occurring in tropical bogs and 

 lagoons, the Purbeck formations consist of numerous 

 alternating shallow layers, with the stumps of the terres- 

 trial dirt-beds penetrating (or rather surrounded by) 

 the fresh-water mud and slates. On the Isle of Portland , 



