Lytton sits at the eastern edge of the Intermontane Belt in the Interior Plateaus. The rocks of this Belt are little changed from when they were first deposited here, and reside no more than 10 kilometres below the surface. Composed mostly of volcanic and sedimentary rocks with granitic rocks, the Intermontane Belt rocks were fused to the continent approximately 185 to 170 million years ago then a mere 10 million years ago, plateau basalts covered the region.
The Fraser Fault System runs up this way from Hope for about 325 kilometres, all the way to Williams Lake. In some places it is a single structure but in others it is a system of interconnected faults that cover an area up to 3 kilometres wide. An exposed conglomerate of greyish green (believed to have originally been reddish brown) can be seen in various spots up Highway 1 where the land has been cut by either man or nature. The Pasayten fault running through Lytton aligns itself with the more youthful Fraser fault system and serves to separate Jackass Mountain rocks of sandstone, shale and some conglomerate from granitic and gneissic rocks of late Paleozoic and early Mesozoic age, defining a boundary between the Intermontane Belt and Coast Belt, and located right near our ferry landing.
Just slightly north on Highway 12, one can see the granitic rocks of the Mount Lytton complex – between 250 and 225 million years old! – fractured and slowly turning pink. About 20 kilometres north of town, one can see Mount Lytton granitic rock that has turned into mylonite, which contains blue quartz “eyes” in some places.
In town, you’ll find the Lytton Jelly Roll, a rare geological phenomenon that results from prehistoric glacial movements. While usually measured in centimetres, our Jelly Roll has its own mural in Caboose Park and is one of the largest in the world. Geologists and their students come from all over the world to see and study it.