Sentence:  ... I trawled my way through the staggering <WSD>amassment</WSD> of papers and journals and tomes that chronicle the newest developments in the astonishingly fast-moving world of modern geology. 
Meaning of the word marked with <WSD> tags:  That which is amassed; a large quantity ("of" something).<ref>(Samuel Johnson), "(A Dictionary of the English Language)," London: W. Strahan, 1755: “A<small>MASMENT</small>. (...) A heap; an accumulation; a collection.”[https://babel.hathitrust.org/cgi/pt?id=ucm.5326809190&view=1up&seq=127&size=150]</ref>