Sentence:  So great is the part played by stratified deposits in the structure of the earth's crust that we might be tempted to speak of the <WSD>"stratosphere</WSD>" of the earth in contradistinction to the "scoriosphere" of the moon. 
Meaning of the word marked with <WSD> tags:  Collectively, those layers of the (Earth)'s (crust) which primarily (comprise) (stratified) (deposits).