A

GEOLOGICAL INQUIRY

RESPECTING

THE WATER-BEARING STRATA

OF THE COUNTRY

AROUND LONDON,

WITH REFERENCE ESPECIALLY TO

THE WATER-SUPPLY OF THE METROPOLIS;

AND INCLUDING SOME REMARKS ON SPRINGS.

BY

JOSEPH PRESTWICH, JUN., F.G.S.,

MEMBER OF THE GEOLOGICAL SOCIETY OF FRANCE;
CORRESPONDING MEMBER OF THE ROYAL GEOLOGICAL SOCIETY OF CORNWALL.

LONDON:

Printed by SAMUEL BENTLEY & Co.

Bangor House, Shoe Lane.

TABLE OF CONTENTS.

I. INTRODUCTORY OBSERVATIONS.

§ 1. OBJECT OF THE WORK.-GENERAL VIEW OF THE SUBJECT

II.-GENERAL PHYSICAL CONDITIONS.

§ 2. ON THE GEOLOGY OF THE COUNTRY AROUND LONDON, WITH REFE-

RENCE TO THE POSITION OF THE WATER-BEARING STRATA

PAGE

11

$3. GEOLOGICAL CONDITIONS AFFECTING THE VALUE OF THE WATER-

BEARING DEPOSITS, ILLUSTRATED IN THEIR APPLICATION TO THE TERTIARY

STRATA

18

III. EXTENT AND STRUCTURE OF THE DIFFERENT DEPOSITS.

§ 10. ON THE RELATION BETWEEN THE ACTUAL AND THE EFFECTIVE

SUPERFICIAL AREAS OF THE SEVERAL WATER-BEARING DEPOSITS

99

§ 11. ON THE FALL OF RAIN-ON THE QUANTITY INFILTRATING BENEATH

THE SURFACE-ON THE POWER OF ABSORPTION AND ON THE PERMEABILITY

OF THE WATER-BEARING STRATA

108

12. ON THE VOLUMES, DIMENSIONS, AND CAPACITY FOR WATER OF

THE SEVERAL WATER-BEARING STRATA

120

V. THEORETICAL CONSIDERATIONS.

§ 13. EFFECTS OF DISTURBANCES OF THE STRATA ON THE SUBTERRA-

NEAN PASSAGE OF WATER

§ 14. ON THE THICKNESS OF THE CHALK, AND ON THE PROBABLE Depth

BENEATH LONDON OF THE UPPER AND LOWER GREENSANDS

PAGE

§ 15. ON THE HEIGHT TO WHICH THE WATER FROM THE UPPER AND

LOWER GREENSANDS WOULD PROBABLY RISE AT LONDON

$ 16. ON THE PROBABLE QUALITY OF THE WATER IN THE DEEP-SEATED

BEDS OF THE UPPER AND LOWER GREENSANDS

143

153

€ 197

ON THE ARTESIAN WELLS IN THE TERTIARY AND CRETACEOUS DIS-

TRICTS OF THE NORTH OF FRANCE.

APPENDIX B.

ON SPRINGS ARISING FROM FAULTS, AND ON THEIR ANALOGY TO AR-

ON THE WATERS OF THE LOWER TERTIARY SANDS AND OF THE CHALK

BENEATH LONDON

216

APPENDIX D.

ON THE RELATION OF THE GEOLOGICAL CHANGES, ACCOMPANYING THE

FORMATION, AND DETERMINING THE LITHOLOGICAL CHARACTER, OF THE

SEDIMENTARY DEPOSITS, WITH THE PRESENT CONDITION OF THE WATERS

IN THEIR WATER-BEARING STRATA

APPENDIX E.

ON THE COST OF SOME ARTESIAN WELLS IN ENGLAND AND ON THE

CONTINENT, WITH REFERENCE TO THE PROBABLE EXPENSE OF SINKING

WELLS OF THIS DESCRIPTION INTO THE UPPER AND LOWER GREENSANDS

BENEATH LONDON

226

233

I. INTRODUCTORY OBSERVATIONS.

§ 1. Object of the work.-General view of the subject.

1. THE attention of the author was first directed to the subject of the present work by the apparent want of sufficient geological information bearing upon the question of “Artesian wells," and by the uncertainty as to their capabilities and value, which seemed to prevail in the discussions of the many plans brought forward in the course of the last few years, for the better supply of water to the metropolis.

Some acquaintance with the Geology of the district, which had led incidentally to an examination of the Artesian wells, joined to the general interest of the subject, was the cause of his engaging in this inquiry; not, however, with any purpose of treating it in that detail which the special nature of the subject would require, but rather with the hope of calling attention to the practical application of Geology in an important economical question, and of establishing some general principles which may serve to guide to further and more exact investigations.

Although since the commencement of this work the several districts have been visited by the author with reference more especially to the object he has had in view, the greater part of the observations recorded in the following pages are the

B