Over sea, under stone

Susan Cooper's Dark Is Rising is one of the best children's fantasy book series ever written, and everyone who likes fantasy should read it.
Yes, it was written quite a long time ago (1965) and the details reflect that, but I read it first time in the 80s, and I didn't feel it was the least old-fashioned or outdated.
Now I'm an adult, I have read it dozens of times, and I still love to reread it, and I still feel the... uneasiness, fear, excitement, worry... One thing though, it felt it took a LOT longer for things to happen back at 80s :-D