2l8 



HARDWICKE'S SCIENCE-GOSSIP. 



form the lower part of what is geologically known as 

 the "Woolwich and Reading beds," and they rest 

 upon the chalk. 



Their thickness at Hayes Common is perhaps 

 from thirty to forty feet, but, owing to the absence of 

 any sections in the central parts of the common 

 reaching to the chalk, the exact thickness cannot be 

 definitely ascertained. Most, if not all, of these 

 pebbles are undoubtedly flints derived from the chalk, 

 rolled and ground down into the form of pebbles. 

 But the sand, which occurs with the pebbles, could 

 not have been derived from the same source. Neither 

 could it have resulted from the attrition of the chalk 

 flints. The absence, moreover, of any chalky matter 

 indicates that the sand was obtained from some other 

 rock. My own opinion is this : during the Lower 

 Eocene period the London basin may have received 

 material resulting from the destruction of rocks in the 

 Wealden area. This would easily explain the origin 

 of the sand on Hayes Common ; and I am the more 

 inclined to believe in this theory from having fre- 

 quently observed in the immediate neighbourhood 

 small pieces of worn ferruginous sandstone, such as is 

 very abundant in the upper greensand at Sevenoaks 

 and other places. Sir Charles Lyell, in his 

 "Elements," expresses it as his opinion, that "con- 

 tiguous parts of the sea were sufficiently deep to 

 receive and retain the matter derived from that 

 waste," (i.e. the denudation of the weald). 



The water by which these beds were deposited, 

 appears to have been subject to a variety of currents, 

 giving rise to what is known as irregular bedding ; 

 and from the general character of the beds, it seems 

 probable that they were thrown down upon a kind of 

 beach which was continually rising. In one or two 

 instances, however, I have met with diagonal bedding, 

 and the dip of the laminae in these cases was toward 

 the east. 



I may note here that the " Thanet sand," which 

 is the lowest member of the Lower Eocene rocks, is 

 not present in this part of Kent, although it occurs in 

 considerable thickness in Mid and East Kent. 



At the base of the pebble beds a thin stratum of 

 clay occurs, inclosing unworn green-coated chalk 

 flints. Upon the surface a thin band of peat, of from 

 two to eight inches thick, has been formed by the 

 dense vegetation of furze and heath. 



No fossil remains of any kind have been found in 

 the pebble-beds proper of Hayes Common ; but the 

 writer has frequently found shells characteristic of the 

 "Woolwich and Reading beds," in a bed of clay 

 situated at the south-eastern extremity of Hayes 

 Common, and exposed in section at Coney Hall Hill. 

 Some time since, a skull (in a rather perfect condition) 

 of the Bos primigenius was found in the gravel 

 occupying the bottom of a valley in the immediate 

 vicinity. 



Perhaps I ought to mention, as an interesting fact 

 in connection with Hayes Common, that recently a 



large number of pits have been noticed which are 

 supposed to be the remains of British "pit dwellings." 

 The writer, having found worked flints on the common, 

 was led to open one of these pits (December, 1878), 

 but nothing of importance was found. Before long, 

 it is hoped, other pits will be opened, and thus some 

 knowledge gained of these interesting remains. 



Deposits of pebble-beds, similar to that at Hayes, 

 are frequently met with in West Kent and Surrey ; 

 and their presence is usually betrayed by the peculiar 

 vegetation which they support. We must not, how- 

 ever, infer that these deposits were once spread over 

 the entire surface of the country. There is good 

 reason to believe that the general features of the 

 country in this neighbourhood remain the same now 

 as when originally deposited and left by the retiring 

 sea. 



It will be seen, therefore, that the geological 

 features of Hayes Common, although lacking in 

 anything of an unusual nature, are not, at least, 

 destitute of some interest, and may, after all, teach 

 the young student of nature some facts worth 

 knowing. 



ORNITHOLOGICAL ESSAYS. 

 No. II. — Sparrowhawk {Accipiter nisits). 



By Tom Wm. Dealy. 



BIRDS of prey form so conspicuous a position 

 in our mountain landscape, that it is no wonder 

 they do not thrive. Shot at, and entrapped by 

 keepers, who have every incentive to wage war 

 a ontrance against these bold depredators, who 

 wonders at their decreasing numbers? Any winged 

 "vermin" which darkens the zealous keeper's path 

 has but small chance of safety. Rewards are offered 

 him for their heads and limbs ; collectors and dealers 

 tempt him to risk his huge form in clambering over 

 precipitous rocks, and gaining dizzy eminences, that 

 he may approach their well-nigh inaccessible eyries. 

 Indeed, when we enumerate the numberless diffi- 

 culties 'this tribe of birds has to contend with, our 

 astonishment is that any remain. 



Conspicuous among this persecuted family is the 

 subject of this essay. It is one of the short-winged 

 hawks. Most of the members constituting the family 

 Falconidse may be termed courageous, and are 

 particularly eminent for their bravery and noble 

 carriage ; but the sparrowhawk carries with this a 

 degree of impudence and daring which makes it the 

 universal terror of the smaller of the feathered tribe. 

 Many are the stories current of the bold, fearless 

 daring of this hawk — of dashing through glass in 

 impetuous pursuit of its intended victims ; of chasing 

 them into rooms, compelling them to take refuge in 

 unlooked-for places, such as flying to man, claiming 

 from him that protection which they cannot find else- 

 where. One poor bird, I remember, "took sanctuary " 



