GULLIVER. — SHORELINE TOPOGRAPHY. 201 



completely surrounded by the aggraded detritus of recent times (Fr., 244, 245). 

 The latter may never have been an island. 



Berneray island in the Hebrides is made up of several higher portions connected 

 by sandy areas (Scot., 89). 



A group between Brandon and Tralee bays (Ireland, IGI). 



Eddy island is a composite island, in which there are two examples of lagoons 

 almost included by tombolos (Ireland, 114, 115). 



Several islands at the head of Galway bay seem to belong to this class 

 (Ireland, 115). 



The type of islands tied to the mainland by delta growth is seen in lougli Swiliy 

 (Ireland, 11), where Inch Top island, 702 feet high, appears to be joined to the 

 mainland on the east side of the bay by the detritus borne down by the small 

 streams. Other knobs to the southeast of Inch Top hill were possibly tied in a 

 similar manner. 



The islands of Paleozoic, Mesozoic, Tertiary, and eruptive rocks are surrounded 

 by the delta deposits of the Danube (Taf. III. Jahrb. k. k. Geol. Keiclis., XL., 18^0). 



From San Pablo point to Richmond point is an island completely joined by 

 marshland (C. S., 5581). In this case streams have evidently aided the tidal cur- 

 rents in filling in between a former island and the mainland. 



North head, McKensies head, and various other islands at the mouth of the 

 Columbia river (C. S., 681", 640), are seen upon inspection of the more detailed 

 charts and Mr. Davidson's sketches* to be tied together to form cape Disappoint- 

 ment, which is in turn tied to the mainland at Chinook point. 



An example in which slight elevation may have helped island-tying is seen at 

 the mouth of the Medjerda river (Tunis, VII, XIII, XIV, XX). 



Oland and Gjol are becoming land tied by river and tidal deposits, probably 

 more tidal than river, since the elevation of the land from which the streams come 

 does not exceed 75 meters (Denm., Nibe). 



An example of complex island-tying is seen on the chart of San Quentin bay. 

 Lower California (II. O., 1043). It would appear that the earliest tying was done 

 wlien the land stood lower than at present, for some of the bars outside of the salt 

 lakes are cliffed. 



10. Bat-bars. 



An Adolescent Feature. ■ — Shore development of a submerged region 

 has been studied as regards island-tying ; a second important feature is 

 now to be considered. It has been shown that when sliore-frrade is 

 attained detritus will be transported along the beach at the foot of cliffs, 

 and tombolos connect many islands with the mainland. As the head- 

 lands are attacked faster than the bay heads on account of their more 

 exposed position, wing-bars will frequently be formed of the detritus 

 from the cliffs. This special form of bay-bars will be considered under 

 Winged Beheadlands.f 



* Pacific Coast Pilot, 1889, 451. t See page 2i:l 



