Why is iceberg lettuce called iceberg lettuce?

Crisphead, also called Iceberg, which form tight, dense heads that resemble cabbage. They are generally the mildest of the lettuces, valued more for their crunchy texture than for flavour. Cultivars of iceberg lettuce are the most familiar lettuces in the USA. The name Iceberg comes from the way the lettuce was transported in the US starting in the 1920s on train-wagons covered in crushed ice, making them look like icebergs.

rhul2008 is right i just searched as well and was away to write it but i won't now i just searched on yahoo iceberg lettuce/meaning of name and got it off of there just incase you don't believe me

because if it wasn't it would be called something else