12 



cases of the Amazon and La Plata, the mud bank ranging down 

 to 1,000 fathoms, but as a rule away from the mouth of the great 

 rivers the water is clear and blue, bright at the surface, and 

 devoid of mud. But supposing we go still further and into deeper 

 water beyond all this, and occupying the very bottom of the 

 ocean, we have a great accumulation analogous to chalk. It is 

 calcareous and is mainly the result of countless generations of 

 globigerina — animals which have lived and died at the bottom of 

 the seas. Thus you see at the bottom of the deepest waters, 

 ranging from say 200 or 300 fathoms near the limits, to a depth 

 of 2,300 fathoms, you have this formation which is absolutely 

 distinct from the mud, sand, and shingle. We must not forget 

 to note the fact that in the very greatest depths — from 2,500 

 fathoms to the greatest depths yet arrived at — we have a deposit 

 of what may be termed oceanic muds — the finer sediments which 

 have taken perhaps hundreds and thousands of years to sink, 

 with slowness, to the bottom. We have definite arrangement in 

 the case of the shingle, we know for certain that it is only near 

 the land ; in the case of calcareous deposits we know they are 

 formed in the depths of the sea, and the mud and sand banks 

 tell their own story of the arrangement of the land. We have in 

 that simple arrangement the key to make out the old geography 

 of Lancashire which I shall hope to put before you this evening 

 as a part of the greater geography of this country. For what- 

 ever we may be in politics we cannot, in our geology, separate 

 our geography in Lancashire from the geography of Ireland and 

 Scotland. 



Passing on to the rocks, which we shall consider this even- 

 ing, and which are familiar to most of us as the sandstones and 

 shale and clay and limestone, they are all of them petrified sand- 

 banks, mudbanks, or shingle beaches or in part petrified calcare- 

 ous portions of deeper accumulations which have been formed on 

 the margins which looked towards the land. In the relation with 

 these over-lapping shingle, sand and mud bear to one another, 

 we have the clue to the ancient geological distribution of land 

 and water. Having then finished that section, the next thing 

 which I must ask your attention to is the classification of the 

 carboniferous formation, consisting of a series of grits. We 

 have first of all the carboniferous shale, then Yoredales, then 

 millstone grits, so named because in comparatively modern times 

 they have been used for making millstones ; and then above that 

 again we come to the most interesting of all — an accumx;lation of 

 rocks, containing coals and familiarly known as coal measures. 

 These represent the names I shall use this evening, and I should 

 like you to note the fact that we classify these beds into two 

 groups — the lower being the carboniferous millstone grits. Let 

 us, as we are dealing with the pure question of local geography 



