Obruchev, V(ladimir) A(fanas'evich)
1924 (1957)
from the dustjacket of the Lawrence and Wishart edition (shown):

This is the thrilling story of a hazardous journey backwards through time, back into pre-history beyond the far distant days of the ape-men, the mammoth and the sabre-tooth tiger, to the ag of the pterodactyl and the dinosaur.

The author, an eminent geologist and member of the U.S.S.R. Academy of Sciences, wrote several scientific romances in addition to a number of standard books on geography and geology.

During his youth he was greatly influenced by the writings of Jules Verne, Conan Doyle and other masters of the tale of fabulous exploits.

His spirited account of the discovery of Plutonia, a fictional picture of the lost world of time, is the sort of well-written narrative that is relished throughout the world by youth, or by those who have retained a youthful zest for this type of yarn.