og98 帮我分析一下A项的成分

sunny20111126

98 (题目全划线)Even though Clovis points,spear points with longitudinal grooves chipped onto their faces,have been found all over North America,they are named for the New Mexico site where they were first discovered in 1932.这个是正确的，但我不明白spear points with longitudinal grooves chipped onto their faces,在句中做什么成分？同位语吗？还是是插入语？修饰Clovis points？Clovis points和spear points是一个东西吗？这句话到底什么意思呢？句中的their faces 到底是谁的faces啊？
还有那个they are named for the New Mexico site where they were first discovered in 1932.中的they 指的是Clovis points吗？那这个代词they与their faces指代一致吗？会不会引起歧义啊，因为前文中longitudinal grooves 也是复数啊？
这道题的意思做题时根本没看懂，求指点一下，非常感谢^_^