1. An anatomical mapping system comprising: a plurality of mapping electrodes configured to detect electrical activation signals of intrinsic physiological activity within an anatomical structure and to generate electrical signals indicative of the detected electrical activation signals; a plurality of mechanical sensors configured to detect local mechanical activity associated with the intrinsic physiological activity and to generate electrical signals indicative of the detected local mechanical activity, wherein each of the plurality of mechanical sensors is further configured to transmit ultrasound signals; a reference mechanical sensor disposed outside of the anatomical structure, the reference sensor configured to receive the transmitted ultrasound signals from the plurality of mechanical sensors and to generate, in response to receiving the transmitted ultrasound signals, an electrical signal indicative of movement, due to the intrinsic physiological activity, of at least one mechanical sensor of the plurality of mechanical sensors; and a mapping processor associated with the plurality of mapping electrodes, mechanical sensors, and the reference mechanical sensor, the mapping processor configured to (1) receive and record the electrical signals indicative of the detected electrical activation signals, the electrical signals indicative of the detected local mechanical activity, and the electrical signals indicative of the movement of the at least one mechanical sensor; (2) associate one of the plurality of mapping electrodes and one of the plurality of mechanical sensors with each recorded electrical signal; and (3) determine activation times of the intrinsic physiological activity based on a correlation of corresponding detected electrical activation signals and mechanical activity, the mechanical activity comprising the movement, due to the physiological activity, of the at least one mechanical sensor.