Geologist Sort

As we grow as geologists, we are beginning to name what we've discovered.  Last week, we used screens to sort rocks into different sizes.  Today we named those different sizes.  The largest of the three sizes are called pebbles.  The medium sized rocks are called gravel.  And the smallest sizes rocks are called sand.  We saw that pebbles, gravel, and sand could still be sorted by size within those named categories.  We wondered...what are rocks larger than pebbles called?  And are there rocks smaller than sand?  Stay tuned!