Annually laminated (varved) lake sediments are excellent archives for paleoclimatic- and environmental history. The annual nature of the varves enables precise time control and extremely high resolution, not only annual but also in seasonal scale. This makes such archives convenient when studying abrupt changes with short periodicities. Due to precise time control the results can be correlated to other high-resolution climate proxies.

A sediment sequence of lacustrine sediments from Lake Kalliojärvi in Central-Finland is annually laminated from present until more than 3300 years back in time. Lake Kalliojärvi sediments are clastic-organic varves which is typical varve type in the study region albeit varve formation is generally quite unusual. The lake is located in boreal zone where the mean temperature of coldest month, January, is around -9°C and warmest month, July, +16°C. The large fluctuation in annual temperature cause snow accumulation during winter time and growing season restricted to mainly summer months. The varves in Lake Kalliojärvi reflect the annual circulation of boreal zone. Varve couplet presenting one year of accumulation consists of the two different types of layers. Layer of fine grained minerogenic material representing spring is forming due to flooding caused by water mass released due to sudden melting of snow. The other layer type representing rest of the year is mainly organic material of autochthonous origin. This kind of environment is very sensitive and thus even small changes of short periodicities in climate or environment is recorded as a change in varve parameters.

The aims of this study are to use modern techniques such as ?-XRF, image analysis and X-ray density of the sediment to improve knowledge of the variable Late Holocene climate and environmental evolution of the study area but also to evaluate the role of the variation in solar activity in climate change during the last 3 000 years.