Mark Stirrup — Recent Changes of Level. 503 



occurrence to a widesp red submergence, whicli extended to con- 

 tinental shores. He assigns the date of this event to a time 

 immediately after the destruction of the Mammoth. 



The evidence, I take it, of these submerged forests is far from 

 corresponding with the interpretation thus given ; for not only are 

 they of different ages, but, instead of supporting any argument for 

 a sudden or rapid sinking of the land, they seem cleai'ly to indicate a 

 progressive subsidence, marked by the distinct beds of peat, clay, sand, 

 or gravel by which they are often accompanied. The changes of 

 the level of the land which these submarine forests indicate no one 

 •would attempt to dispute ; but to affirm their contemporaneous 

 growth, or attempt to synchronize them with the end of the Mam- 

 moth period for the purpose of sustaining some fancied theory, is 

 scarcely permissible or scientific. 



That the peat and forest beds took a long time for their accumula- 

 tion and growth might be proved from many of the instances cited 

 by Sir Henry, having regard to the thickness of the deposits and the 

 character of the plant remains, which, in some instances, indicate 

 climatic changes of considerable duration. 



That some of these sunken forests are of an age far more recent 

 than that of the Mammoth, is shown by the prehistoric and Eoman 

 remains that have been occasionally extracted from them. 



The difficulty attending the examination of submerged forests 

 prevents researches which might prove of great interest with regard 

 to their history, therefore those claim special attention which have 

 been exposed to the light of day, such as those due to the dock 

 excavations at Hull and Grimsby. A concise account of the sections 

 is given in the memoir of the Geology of Holderness, by Mr. 

 Clement Reid. Dr. Foster, writes Mr. Eeid, thus describes the beds 

 exposed in the Albert Docks at Hull : — " In the cuttings at the east 

 end the upper stratum is silt, .... and immediately under the silt, 

 the trunks, roots, and branches of Oak trees, together with a peat 

 soil of two feet in thickness, beneath that a strong clay soil, and 

 under this an extensive bed of blue sand, etc." 



"At a depth of 40 feet below the level of the adjoining land, trees 

 (chiefly Oak) are found in all positions; those which are upright 

 and still in situ having been broken off within three feet of the roots. 

 One Oak tree, of noble dimensions, is perfectly straight, its trunk 

 being 45 feet long, and in the thickest part measuring 12^ feet in 

 circumference ; it is tolerably sound, but blackened in colour." 



" The trees .... would require at least 300 years to attain the 

 dimensions given." 



A section taken during the excavation for the Alexandra Docks, 

 two miles lower down the Humbei", exposes the "Submerged 

 Forest " at upwards of 20 feet below the level of mean tide. 

 Messrs. Wood and Rome (Quart. Journ. Geol. Soc, vol. xxiv. p. 146) 

 state that " the borings at Grimsby Docks disclosed the forest-bed 

 at still greater depths than at Hull, varying at from 35 to 52 feet 

 below high water .... In some parts there were two forest surfaces, 

 divided by a bed of leafy clay from 6 to 15 feet thick." 



