(2014•九江三模)如图,四棱柱ABCD-A1B1C1D1的底面ABCD是菱形,AC,BD交于点O,A1O⊥平面ABCD,A1A=BD=2,AC=2
2
(1)证明:A1C⊥平面BB1D1D;
(2)求三棱锥A-C1CD的体积.