Radar 2,963 Radar echoes 1,472 Radar methods 2,835 Radar photography 284 RADARSAT 395 Radiation 347 Radiation absorption 641 Radiation balance 804 Radiation--Cosmic 367 Radiation--Solar 898 Radioactive age determination 3,977 Radioactive isotopes 5,482 Radioactive wastes 461 Radioactivity 308 Radio communication 437 Radio echo soundings 641 Radiolaria 313 Radiometry 1,764 Railroads 1,196 Railroad tracks 271 Rain 1,482 Rainfall 830 Rare earths 627 Rates 1,263 Ratios 281 Rb/Sr 255 Recharge 309 Reconstruction 2,856 Recrystallization 235 Reflectance 288 Reflection 358 Reflection methods 545 Reflectivity 666 Regional 542 Regional planning 543 Regolith 343 Regression analysis 751 Regulations 383 Reinforced concretes 699 Relative age 742 Relief 720 Remanent magnetization 273 Remediation 709 Remote sensing 11,037 Report 1,113 Reproduction 578 Research 1,461 Research facilities 398 Research programs 279 Research programs--Australia 327 Research programs--International 879 Research programs--Japan 292 Research programs--United States 696 Research programs--USSR 464 Research projects 2,775 Reservoir rocks 324 Reservoirs 727 Residential buildings 689 Resistivity 561 Resources 251 Respiration 289 Revegetation 1,002 Review 499 Reviews 775 Rheology 1,352 Rifting 468 Rift zones 341 Risk assessment 1,884 Risk management 688 River basins 2,564 River flow 1,851 River ice 3,520 RIVER ICE 310 Rivers 1,231 Rivers and streams 987 Roadbeds 560 Road icing 1,303 Road maintenance 2,354 Roads 3,146 ROADS 319 Rock glaciers 1,036 Rock mechanics 651 Rocks 368 Roofs 668 Roots 244 Rotaliina 485 Rotation 233 Roughness 251 Runoff 4,397 Runoff forecasting 1,056 Runways 353 Russia 1,422 Russia--Kara Sea 361 Russia--Kola Peninsula 393 Russia--Lena River 312 Russian Republic 285 Russia--Russian Arctic 1,522 Russia--Siberia 700 Russia--Yakutia 544 Russia--Yamal 228