More accurately, "bergs," as scientists call them, come from glaciers, which are like slow moving rivers of ice formed by thousands of years of snow that never melted.
(scientists; call; them) (thousands of years of snow; never melted; ) (scientists; come; from glaciers) (glaciers; are; like slow moving rivers of ice) (slow moving rivers of ice; formed; by thousands of years of snow)
scientists thousands of years of snow scientists glaciers slow moving rivers of ice
call never melted come are formed
them
from glaciers
like slow moving rivers of ice
by thousands of years of snow