Radar 2,622 Radar echoes 1,594 Radar methods 2,501 Radar photography 299 RADARSAT 381 Radar tracking 215 Radiance 206 Radiation 361 Radiation absorption 677 Radiation balance 868 Radiation--Cosmic 426 Radiation--Solar 928 Radioactive age determination 3,739 Radioactive fallout 211 Radioactive isotopes 4,065 Radioactive wastes 468 Radioactivity 274 Radio communication 440 Radio echo soundings 849 Radiometry 1,873 Radio waves 218 Railroads 1,194 Railroad tracks 276 Rain 1,456 Rainfall 742 Rare earths 368 Rates 770 Recharge 248 Reconstruction 2,255 Reflectance 217 Reflection 244 Reflection methods 362 Reflectivity 639 Regional planning 534 Regolith 334 Regression analysis 642 Regulations 371 Reinforced concretes 705 Relative age 563 Relief 616 Remediation 659 Remote sensing 10,421 Report 1,017 Reproduction 571 Research 1,227 Research facilities 424 Research programs 301 Research programs--Australia 344 Research programs--International 979 Research programs--Japan 310 Research programs--New Zealand 196 Research programs--United States 747 Research programs--USSR 478 Research projects 2,972 Reservoir rocks 271 Reservoirs 770 Residential buildings 692 Resistivity 426 Respiration 283 Revegetation 1,054 Review 253 Reviews 846 Rheology 1,485 Rifting 258 Rift zones 204 Risk assessment 1,847 Risk management 688 River basins 2,424 River flow 1,890 River ice 3,588 RIVER ICE 314 Rivers 1,182 Rivers and streams 759 Roadbeds 570 Road icing 1,316 Road maintenance 2,378 Roads 3,055 ROADS 328 Rockets 228 Rock glaciers 1,046 Rock mechanics 639 Rock properties 251 Rocks 453 Roofs 670 Roots 242 Rotaliina 370 Roughness 224 Route surveys 209 Runoff 4,378 Runoff forecasting 1,188 Runways 364 Russia 1,410 Russia--Kara Sea 417 Russia--Kola Peninsula 381 Russia--Laptev Sea 267 Russia--Lena River 296 Russia--Russian Arctic 1,469 Russia--Siberia 812 Russia--Yakutia 485 Russia--Yamal Peninsula 196