Base matrices of various heights

A classical theorem of Balcar, Pelant, and Simon says that there is a base matrix of height h, where h is the distributivity number of P(omega)/fin. We show that if the continuum c is regular, then there is a base matrix of height c, and that there are base matrices of any regular uncountable height less or equal than c in the Cohen and random models. This answers questions of Fischer, Koelbing, and Wohofsky.