IAH (NZ Chapter) Technical Meeting – Christchurch

Members and non-members welcome to this free event!

5:00 pm networking, 5:30 pm technical talk
Tuesday 24th February 2026

Tonkin & Taylor, Level 2, Awly Building, 293 Durham Street North, Christchurch

(Please arrive before 5:30 pm for T+T staff to let you in. Late arrivals, please text Sally Lochhead 0275114321)

Please RSVP to Sally Lochhead by 19 February for catering purposes.

Presenter: Carl Hanson (Environment Canterbury)

Late-Quaternary stratigraphy of the Christchurch Artesian System, coastal Canterbury Plains, New Zealand

Profile: Carl has 35 years’ experience as a groundwater scientist, more than 20 of those leading groundwater quality science at Environment Canterbury. He holds a Master of Science degree in geology from Dartmouth College, USA.

Abstract: The late-Quaternary stratigraphy of the Christchurch Artesian System (CAS), located along the coast of the northern Canterbury Plains, New Zealand, is formally extended. Six new formations – three interglacial formations and three glacial climate formations – are identified and described. The sequence is recognised in water well logs that extend to depths of up to 250 m, where the Pliocene-Pleistocene Kowai Formation unconformably underlies the sequence and marks the base of the CAS. The new formations underlie the Wainoni Gravel and correlate with international marine isotope stages (MIS) 11-16. The three new interglacial, coastal-marine, fine-sediment units do not extend further inland than the interglacial units in the overlying MIS 1-10 sequence. The three new glacial gravel units and gravel aquifers merge westwards into the continuous sequence of alluvial gravel, sand and silt sediments underlying the inland Canterbury Plains. West of the CAS, it is impossible to distinguish stratigraphic units in bore logs, and the middle- to upper-Quaternary sediments are undifferentiated gravel deposits. This improved stratigraphic knowledge of the sediments beneath Christchurch is important for the sustainable management of the CAS groundwater resource.

Come along and hear how geoscientists delved deeper into the Christchurch Artesian System, one of New Zealand’s most important freshwater resources.

Online Attendance

Those in Christchurch are expected to join in person for drinks, nibbles and networking. For those outside Christchurch who cannot attend in person:

Meeting ID: 421 522 489 650 87 | Passcode: oh6Wt2CR