HOPKINS ON THE LAKE DISTRICT. 93 
spherical, as many erratic blocks are observed to be, there is no doubt 
that blocks of 5 tons and upwards might be moved by a current of 10 
miles an hour; and, assuming the force of the current to increase at 
the square of the velocity for greater velocities than that, it follows 
that a current of 15 miles an hour would move blocks of similar 
forms of the weight of 56 tons and upwards; while a current of 20 
miles an hour would move similar blocks of 320 tons and upwards. 
For other forms the weights might be much less ; but these calcula- 
tions demonstrate beyond doubt, that while an ordinary stream of 
between 2 and 3 miles an hour may be insufficient to move a pebble, 
a current of from 10 to 20 miles an hour may have motive power 
sufficient to transport blocks of enormous magnitude. 
24. Application of the preceding theory.—In the practical appli- 
cation of these views, the great wave of translation and its attendant 
current are to be attributed to the elevation of the district whence 
the blocks have been conveyed previously to its emergence above the 
surface of the sea. We must further suppose such elevation to have 
been sudden, of a paroxysmal character, in which case the height of 
the wave would be approximately that of the elevation, as already 
stated. Its breadth would depend on the extent and form of the 
elevated area. If we suppose that area approximately circular, and 
the wave to diverge freely, its breadth would be at least equal to the 
radius of the area, and might be considerably greater. We thus see 
how diverging currents, of enormous transporting power, may be 
simply accounted for. Nor does this view of the subject require the 
hypothesis of paroxysmal elevations of great magnitude ; for it ap- 
pears, from what has been stated, that an elevation of 100 or 150 
feet would produce a current capable of transporting, for at least a 
short distance and under favourable conditions, a block of immense 
weight. 
The hypothesis respecting these elevations which may be deemed 
most favourable to this theory of transport, is, that they were par- 
oxysmal and frequent, but not necessarily large. The effectiveness of 
this cause will also be increased if we suppose these successive ele- 
vations to have been attended (as they probably must have been) 
with alternations of subsidence ; for in such case it may have re- 
quired a much greater number of these paroxysmal elevations to pro- 
duce as their result an existing elevation of given magnitude, than if 
they had been unattended by frequent subsidence. 
I have already explained my reasons for believing the inadmissi- 
bility of the glacial theory to account for the phenomena of the 
blocks of Shap granite. In adopting either of the other theories we 
must necessarily suppose the pass of Stammoor to have been beneath 
the surface of the ocean at the period of transport of these blocks. 
I have also stated my reasons (Art. 11 (6.)) for believing that the 
district of the Lakes had scarcely begun to emerge from the ocean at 
the epoch at which the transport of boulders may have commenced, 
i.e. not long after the deposition of the new red sandstone. Accord- 
ing to this view, therefore, there must have been, since that period, 
an elevation of the centre of the district of 1500 or 2000 feet over and 
