CHAP. XXXVII.] IN COAL STRATA. 309 



mud thrown down by every tide on the borders of 

 estuaries connected with the Bay of Fundy. When 

 this mud, which extends over thousands of acres, has 

 been baked by the hot summer sun of Nova Scotia, 

 it shrinks and cracks to the depth of several inches or 

 even feet, and acquires such consistency as to be 

 divisible into the successive layers of which it is com 

 posed, presenting on many upper surfaces impres 

 sions of birds feet and cracks, and on the undersides 

 the casts of the same standing out in relief.* 



I have also stated f that on the sea beach near 

 Savannah, in Georgia, I saw clouds of fine sand 

 drifted by the wind, filling up the foot-prints of 

 racoons and opossums, which a few hours before had 

 passed along the shore, after the retreat of the tide. 

 This process will account, in a satisfactory manner, 

 for the sharpness of many fossil casts of animals in 

 ancient rocks, as the grains of uniformly fine sand 

 were poured into the newly made cavities, not by a 

 current of water, which could scarcely have failed to 

 disturb the soft mud, but by the air, which could not 

 cause the slightest derangement of the most delicate 

 imprints. 



No less than twenty-three foot-steps were observed 

 by Dr. King on slabs in the stone quarry of Union 

 township before mentioned, before its abandonment, 

 and the greater part of these were so arranged (see 

 fig. 13.) as to imply that they were the marks of the 



* I have presented specimens of this red mud, with the foot 

 prints of birds, to the British Museum, Geological Society, and 

 Museum of Economic Geology. 



t Travels, vol. i. p. 167. 



