66 NOTES — ORIGINAL AND SELECTED. 



End, visited during our excursion to Writtle. There are also some 

 fine pits in it near the water-tower south of the town. 



These constituents of the Glacial Drift hereabouts, the Sand and 

 Gravel Beds and the Boulder Clay, vary very considerably in thick- 

 ness. We may also discover that in one place Boulder Clay lies 

 directly on London Clay, while in another the Sand and Gravel has 

 but a few small patches of Boulder Clay resting upon it. But a 

 glance at the map of the Geological Survey shows the close associa 

 tion of the two formations, and makes it evident that they both 

 belong to the same geological period, though there may be nothing 

 in any sections to stamp the Sand and Gravel series as Glacial, in 

 the sense in which the Boulder Clay is rightly so termed. As 

 regards the variations in thickness of these constituents of the 

 Glacial Drift, I learn from the Geological Survey Memoir, on Sheet 

 47, that "in wells at Scravels, near Broomfield, there are 12 feet of 

 gravel, and at Broomfield School 18 feet, covered respectively by 3 

 and 7 feet of Boulder Clay." And near Great ^Valtham Church the 

 gravel is more than 24 feet thick ; at Great Leigh's Parsonage, 20 

 feet ; and 5 furlongs east of it, 30 feet of gravel were found under a 

 like thickness of Boulder Clay. At Troys Hall, Fairsted, there were 

 60 feet of Boulder Clay above but i| foot of gravel. 



Formerly the Chalky Boulder Clay was much used for marling 

 the land, and the old marl pits continue to furnish sections, though 

 they have become disused as sources of manure. Inspection of 

 some of them will show how much the uppermost two or three 

 feet have been deprived of the Chalk they once contained through 

 the action of the weather. The depth to which the Chalk has been 

 dissolved away is variable, as it depends on the greater or less per- 

 meability of the Boulder Clay at any given spot. 



NOTES— ORIGINAL AND SELECTED. 



Capture of Otters near Chelmsford.— "The Essex County Chronicle'" of 

 May 1 2th, records that on " Monday afternoon, May 8th, a man named Abbott, 

 in the employment of Mr. G. B. Ling, caught a young otter in the head-water at 

 Springfield Mill, Chelmsford. The animal, which is about three months old, is 

 being kept alive. The same afternoon, also, some pupils at the Arc Works 

 caught a small otter in the river at Chelmsford."' 



Uncommon Birds near Birchanger.— Mr. A. P. Church, in a letter 

 recently received, says : " It may interest you to know that we have a pair of 

 Green Woodpeckers breeding within a very few yards of our house at 



