EARTHQUAKES AND SUBSIDENCES IN NORFOLK. 
By Horace B. Woodward, F.G.S. 
(Of the Geological Survey of Englarul). 
Read 2^th March, 1884. 
In the peaceful agricultural county of Norfolk our thoughts arc not 
often directed to those grand and awful workings of Nature, else- 
wliere too well known in the form of volcanoes. Happily for us, 
and for mankind in general, the districts ravaged by volcanic action 
have remained very much the same during historic times. Never- 
theless here and there the associated phenomena of eartlupiakes 
have unexpectedly and painfully aroused attention to the instability 
of the earth’s crust, and led to the uncomfortable feeling that homo 
on terra firma (in certain situations at any rate) may be no more 
secure than life on the ocean Avave. 
A study of the geological history of England clearly proves that 
our country luis during several epochs in the past been affected by 
great volcanic eruptions. The fiery records arc preserved more 
l)articularly in the hilly country that lies to the north and west ; 
and they are to be deciphered from the old lava-flows and ash-beds, 
and the altering or metamorphism of neighbouring stmta. 
Long ages have elapsed since the last of these eruptions, but even 
in our own county some of the relics have been handed down to us. 
An old Avriter remarked, on account of the variety of its soils, that 
“ all England may be carved out of Norfolk,” and to a certain 
extent this has really taken place. For the boulder clays and 
gravels, so Avell shoAvu in the cliff sections east of Weybourn, and 
scattered over the length and breadth of the county, contain 
fragments from nearly every British rock-fermation. And among 
these Ave find boulders of gnmite, gneiss, mica-schist, basalt, and 
greenstone, that tell the bile of volcanic action in the distant past 
Avhen their parent rocks AA'crc formed, altered, or erupted.* 
* Some of the igneous and metamorphic rocks are probably of Scandi- 
navian origin. 
