Page 

 I 

 I 



CONTENTS 



I. Introduction 



Objectives and results 



Acknowledgments 



II. The trees used ^ 



Location and environment 3 



Lubbock, Texas, and vicinity 3 



Mountains of northern New Mexico 5 



Chisos Mountains of southwest Texas 5 



Yuma, Arizona ^ ^ 



The vicinity of Washington, D. C 1 1 



Tree descriptions ^ ^ 



Locality symbols ^ ^ 



Species symbols ^^ 



III. The methods used 2° 



Macroscopic methods ^^ 



Microscopic methods ^ 



IV. Absolute dating— criteria of multiplicity 23 



Discovery of precise dating ^3 



Methods of absolute dating 24 



Natural frost efif ects 24 



Artificial frost ^7 



Tip-growth measurements • • 28 



Number of diameter flushes in relation to number of tip 



flushes 31 



Correlation of structural features 32 



Summary statement 32 



V. Classification of growth layers 23 



Introduction 33 



Constituents of a growth layer 35 



Terms 35 



Reaction or compression wood 38 



Contacts between growth layers 38 



Types of contacts 3° 



Features causing diffuse contacts 41 



Variable contacts 5^ 



Densewood stringers 54 



Completeness 55 



Summary and conclusion on contacts 55 



Classes and types of growth layers 56 



Entire growth layers 5^ 



Partial growth layers 58 



Summary of classification and types 99 



Longitudinal variations 99 



Summary of types i ^^2 



Type relationships ^ ^3 



Ecologic significance ^ ^4 



Definition of a growth layer 120 



V 



