WOOOHOO! You and your friends have just won a lottery for airplane tickets to Hawai'i for spring break. You are especially excited to visit the famous green sand beach on the Big Island. Your friend asks, "Why are these beaches so rare? Why aren't green sand beaches everywhere?" To answer their question, consider: • the likely mineral composition of green sand beaches compared to "typical" beach sand; • the source of the sand. (Hawaii is made of basalt, and not much else. Most continental bedrock is, on average, more like diorite or granite); • how far sand might travel from the source to the beach; and, importantly; • how physical and chemical weathering can influence which minerals are preserved in sand. (Remind yourself by consulting Bowen's Reaction Series.) Once you have organized your thoughts, draw and annotate a picture (or series of pictures on one page) to explain why green sand beaches are so rare, addressing the concepts in the list above. (Hint: a triangular diagram is important here...)
