A key advantage of the records described in this chapter is the ability to carry out many different types of laboratory analyses on the same profiles. These multiple proxies—physical, biological, or chemical—can have different and independent bases for climatic calibration; they include the use of modern training sets, sediment trap studies, and historic calibration. Some, but not all, marine, lake, peat, and cave records have annual time resolution. Those that do not have annual dating may nonetheless be able to capture low-frequency climate fluctuations (Moberg et al. 2005b). A major challenge in these cases is to ensure that records are accurately dated and correlated because, if they are not, composite records will tend to smooth out the true temperature variability.