A SEASIDE RAMBLE 217 



variety of silica, i.e. quartz crystals. These lined 

 with chalcedony also are very beautiful. 



I generally find traces of sponges in all flints lined 

 with this beautiful mineral. But we shall not have 

 to look very long before we find the ancient glass 



Fig. "58. Silicified Sponges in Flint. 



sponges, which lived when warmer waters occupied 

 the place of this Channel and of the land on which 

 we are walking. Glass or flint sponges lived in large 

 numbers about here on an ocean bed. Their bodies 

 in every detail have been succeeded by flint, and so 

 marvellously quietly has the change taken place that 



