About the book What is the inside of the Earth like; what mysteries does its mantle conceal? What will the sensitive feelers of superdeep holes encounter there - boiling liquid magma or superhard matter, unimaginably high temperatures or cold approaching absolute zero?Science cannot as yet give the exact answers to these questions, though myriads of different hypotheses have been put forth.This book tells how scientists are ferreting out the secrets of the deeper zones of the Earth; its subject is the romance of the searches and tenacious investigations carried out by geologists who have devoted themselves to the study of the depths of our planet. CONTENTSRiddles and More RiddlesAn Argument 9 In the Fiery Font 12 The End of Gondwana Land 25 Rock Rhythms 35 Laws or Riddles? 43 The Black Arteries of the Depths 52 What the Neoneptunists Say 60 “We Must Not Wait for Favours.” 68Flow of InformationA Signal into the Unknown 79 Key to the Gravity Code 100 Heat and Cold 112 You Will Not Find This in Any Textbook 119 Stray Currents 120 Hall! Radioactivity! 134 First Results 143 From Outer Space into the Depths of the Earth 145In Search of the UnknownFailures at First 161 Geography of the Unknown 166 The First Stone Tells Its Story 171 The Stone from the Kola Speaks 179 The Story of the Third and Fourth Stones 185 A Message from the Fifth Stone 190 Courtiers of the “Queen of the Depths” 194 An Artificial Mantle 203 And Here, Too, Synthesis 208The World of Unsolved RiddlesFollowing in the Footsteps of the Classics 219 If the Magmatists are Right 224 Hardness Also Has Its Limit 231“There’s No Magma Under the Crust!” 234 Beyond the Moho Discontinuity 240 But Who is Right? 243