Our understanding is poor of the timing of major events that shaped the Cairngorms. This uncertainty reflects the fact that the mountains have been an area of net erosion for much of the last 50 million years.
The relative age of landforms and sediments can be inferred from cross-cutting relationships. For example, the fact that corries are cut into the edges of the plateau shows that the general form of the plateau is an older feature. Similarly, the way in which some tors have been modified by ice indicates that their formation predates at least the last ice sheet.
The general sequence of events in this part of Scotland can be pieced together from evidence from elsewhere. The timing of Tertiary uplift is evident from research in the Tertiary Igneous Province in Arran, Skye, Mull and elsewhere. The onset of glaciation at the end of the Quaternary is recorded in deep ocean sediments in the North Atlantic and the fluctuations of Ice Age climate are seen in the Greenland ice cores.
Some evidence of events in the mountains comes from the sediment receiving area in the Central North Sea. Regional glacial chronology also helps to constrain the timing of events in the Late Quaternary.
Until recently, radiocarbon dating was one of the few ways to date directly sediments and events in the Cairngorms. With a half life of 5730 yr, radiocarbon dating is limited to organic materials from the last 50-30 kyr. The arrival of new techniques, such as luminescence dating and cosmogenic exposure ages, with potential to explore time periods of 10-100 kyr, heralds the possibility of new steps forward in understanding rates and styles of landscape change in the Cairngorms.
A detailed account of the Scottish Quaternary provided by SNH is here.