Is it unusual to find slate in the Sierras at the 1000 meter elevation?

I found large outcroppings of slate on my ranch, which is at the 1000 meter elevation in the Sierra Nevada Mountains in California, about 50 miles east of Fresno. All of the rock outcroppings I have seen around here are granite, so I was surprised to see slate. I researched slate on the Wikipedia to find out it was a sedimentary rock. So I am wondering how it got to this elevation, perhaps it was glacial movement during a past ice age? I was wondering if this slate may have some unique microbial fossils, can I see these fossils under a microscope?