The fossils preserved in the rock strata of the Grand Canyon have accumulated for a billion years and provide an invaluable geologic record.
I wonder why “provide” is not “provided”. I think “provide” has to be provided because there’s “and”. And the verb before “and” is “have provided”
I’ve been understood that a tense of the verb before “and” has to be the same tense as the verb after “and” Or it just has to be only the same type of speech not the same tense ?