These links are links to my Google Drive account and these are the books and material which i and some of my friends (you can know who they are on page "about us")used to prepare for IESO 2016.
I personally recommend this Video Series for anyone who has no formal education in Earth Sciences
Start off with the book:- High School Earth Science
Now next set of materials dig deeper into specific areas of earth sciences.
I will add notes on the sequence in which someone should study the books in specific areas.