Smithsonian Report, 1964. — Lyttleton 



PLATE 1 



These strata of sedimentary rock would be horizontal when first deposited. Changes in 

 the Earth's crust as it shrinks cause thrusting, folding, and compression of the rock 

 layers. These distortions of rock are found on every scale from relatively small changes 

 like this to whole mountain ranges such as the French Alps. 



The Earth probably developed from a cool, low density cloud of gas and dust such as the 

 one shown here in the "horsehead nebula" in Orion. Subsequent heating and formation 

 of a liquid core would have caused the Earth to contract. 



