THE LOWER GREENSAND 27 



All the shells we have found are of sea creatures, and 

 show us that the Greensand was a marine formation. 

 But the strata were formed in shallow water not far from 

 the shore. We have learnt that coarse sediment like sand 

 is not carried by the sea far from the coast. And a good 

 deal of the Greensand is coarser than sand. There are 

 numerous bands of small pebbles. The pebbles are of 

 various kinds ; some are clear transparent quartz, bits of 

 rock-crystal more or less rounded by rolling on the shore 

 of the Greensand period. These go by the name of Isle 

 of Wight diamonds, and are very pretty when polished. 

 Another mark of the nearness of the shore when these 

 beds were laid down is the current bedding, of which a 

 good example may be seen in the cliff at the north of 

 Shanklin parade. It is sometimes called false bedding, 

 for the sloping bands do not mark strata laid down 

 horizontally at the bottom of the sea, but a current has 

 laid down layers in a sloping way, it may be just over 

 the edge of a sandbank. Again notice how much wood is 

 to be seen in the strata. Land was evidently not far off. 

 All along the shore you may find hard pieces of mineralised 

 wood, the rings of growth often showing clearly. Fre- 

 quently marine worms have bored into them before they 

 were locked up in the strata ; the holes being generally 

 filled afterwards with stone or pyrites. 



The wood is mostly portions of trunks or branches of 

 coniferous trees. We also find stems of cycads. There 

 has been found at Luccombe a very remarkable fruit of 

 a kind of cycad. We said that in the Wealden period 

 none of our flowering plants grew. But these specimens 

 found at Luccombe show that cycads at that time were 

 developing into flowering plants. Wonderful specimens 

 of what may almost be called cycad flowers have been 

 found in strata of about this age in Wyoming in America ; 

 and this Luccombe cycad, called Benettites Gibsonianus, 

 shows what these were like in fruit. Remains of 



