  With a view toward sub-Riemannian geometry, we introduce and study H-type
foliations. These structures are natural generalizations of K-contact
geometries which encompass as special cases K-contact manifolds, twistor
spaces, 3K contact manifolds and H-type groups. Under an horizontal Ricci
curvature lower bound, we prove on those structures sub-Riemannian diameter
upper bounds and first eigenvalue estimates for the sub-Laplacian. Then, using
a result by Moroianu-Semmelmann, we classify the H-type foliations that carry a
parallel horizontal Clifford structure. Finally, we prove an horizontal
Einstein property and compute the horizontal Ricci curvature of those spaces in
codimension more than 2.
