SGU K 513–516 K 513–516 Beskrivning till jordartskartorna 13H Gävle NV, NO, SV och SO Martin Sundh & Birgitta Ericsson Beskrivning till jordartskartorna SV och NO, Gävle SO 13H NV, K 513–516 Beskrivning till jordartskartorna 13H Gävle NV, NO, SV och SO Martin Sundh & Birgitta Ericsson DESCRIPTION TO THE QUATERNARY MAPS 13H Gävle NV, NO, SV and SO Sveriges geologiska undersökning 2015 ISSN 1652-8336 ISBN 978-91-7403-325-0 Närmare upplysningar erhålls genom Sveriges geologiska undersökning Box 670 751 28 Uppsala Tel: 018-17 90 00 Fax: 018-17 92 10 E-post: [email protected] Webbplats: www.sgu.se Omslagsbild: Strandvallar i kalkstensgrus på Limön. Foto: Birgitta Ericsson. © Sveriges geologiska undersökning, 2015 Layout: Jeanette Bergman Weihed, SGU INNEHÅLL Inledning .................................................................................................................................................... 5 Kartläggningsmetod ............................................................................................................................ 5 Berggrunden ........................................................................................................................................... 9 Berggrundsgeologisk översikt ................................................................................................................ 9 Gävlesandsten och ordovicisk kalksten .............................................................................................. 9 Beskrivning av jordarterna inom kartområdet ...................................................................... 10 Berg i dagen och tunt eller osammanhängande jordtäcke ........................................................... 10 Isräfflor och isrörelser .............................................................................................................................. 13 Morän ........................................................................................................................................................... 16 Utbredning och ytformer ................................................................................................................. 17 Moränens mäktighet ......................................................................................................................... 18 Moränens sammansättning ............................................................................................................. 18 Moränens kalkhalt ............................................................................................................................. 21 Enstaka stora block ................................................................................................................................... 25 Isälvssediment ........................................................................................................................................... 26 Årsundaåsen ........................................................................................................................................ 27 Gävleåsen–Hedesundaåsen ............................................................................................................. 28 Uppsalaåsen .......................................................................................................................................... 32 Västlandsåsen ....................................................................................................................................... 36 Glaciala- och postglaciala finkorniga sediment .............................................................................. 37 Svallsediment .............................................................................................................................................. 40 Älv- och svämsediment ............................................................................................................................ 42 Vindsediment ............................................................................................................................................. 43 Tor v ................................................................................................................................................................ 44 Källor ............................................................................................................................................................. 47 Mäktighetsuppgifter .......................................................................................................................... 47 Inlandsisens avsmältning och strandförskjutningen ......................................................... 47 Gävleproblemet i svensk kvartärgeologi ............................................................................................ 50 Räfflor .................................................................................................................................................... 50 Morän på störd lera ........................................................................................................................... 51 Ändmoränerna .................................................................................................................................... 51 Isälvsgrus på varvig lera, Åbyfors ................................................................................................... 52 Gävleåsens avböjning mot öster ..................................................................................................... 52 Störd varvig lera .................................................................................................................................. 52 Övriga omständigheter ..................................................................................................................... 52 Strandförskjutningen ............................................................................................................................... 53 Geologiska sevärdheter .................................................................................................................... 54 1. Längs nedre Dalälven .......................................................................................................................... 54 2. Billudden, Billhamn, Brämsand ...................................................................................................... 56 3. Gävleåsen ................................................................................................................................................. 58 4. Öarna ....................................................................................................................................................... 58 5. Lisselåsklack ........................................................................................................................................... 61 6. Hille klack ............................................................................................................................................... 61 7. S:t Olofsstenen ....................................................................................................................................... 61 8. Flyttblocket vid Lunds fäbodar ........................................................................................................ 63 9. Gustavsmurarna och Bultbomurarna ............................................................................................. 63 10. Lomsmuren ........................................................................................................................................... 63 11. Myrarna öster om Öjaren ................................................................................................................. 64 12. Jättegrytorna vid Varva ..................................................................................................................... 64 13. Lerviks källa ......................................................................................................................................... 65 14. Hilleviks hälsokälla ............................................................................................................................ 66 15. Kungskällan .......................................................................................................................................... 66 16. Klapphuskällan .................................................................................................................................... 68 17. Kraftkällan ............................................................................................................................................ 68 Summary ................................................................................................................................................... 69 Mapping methods ..................................................................................................................................... 69 Bedrock ......................................................................................................................................................... 70 Glacial striae ................................................................................................................................................ 70 Till .................................................................................................................................................................. 70