Highs and lows (8)
(Other definitions for extremes that I've seen before include "Outlying parts" , "Go to these to be immoderate." , "Fanatics go to these" , "Sex meter (anag.)" , "They are said to meet" .)
(Other definitions for ranges that I've seen before include "Areas for shooting practice" , "Large tracts for livestock in the US" , "Large tracts of open land" , "Series of hills or mountains" , "Chains of mountains" .)